A chainsword is a chain sword. Now, granted, that's not really a future technology, it's a technology we have access to but do not use because it is stupid. A melee weapon which has limited fuel, is horribly balanced, much heavier than normal, and designed to slooooowly carve through things that are much more dense than all the vital juicy bits of a human being? Basically the worst melee weapon you could ask for. But it's stupid awesome and uncommon so 40k can say that chainswords are better than regular swords even though they aren't at all, because 40k is space fantasy and doesn't have to be consistent to the real world, only itself (and even then, it only has to be consistent to itself within a single product, since each product explicitly has license to alter lots of details of the canon). The general path of 40k is normal thing->future thing->thing which is basically the same as normal thing but with space word in front. Machine gun? Pathetic. Laser gun? Getting somewhere. Machine gun but we call it a bolter? Great. Sword? Pathetic. Chainsword? Getting somewhere. Sword but we call it a powersword? Great.

Autoguns are more versatile than Lasguns, with the proper logistical support. However, Lasguns are way easier on your logistical support structure, once you can mass produce them and their powerpacks.

Lasguns are better for the Imperial Guard because of the logistical issues involved.

That said, lasguns can be effectively silenced by making them 'whisperbolt' las weapons ... which is fluff and logic madness.

Actually in fluff a lot of people prefer "machine guns" over lasguns since they are more versalite, have better selection of ammo (from ammo that can pierce armor to ammo that can cut your limbs) and overall have the same stoping power (in fluff) as lasgun. In mechanical side autoguns are same as lasgun while the later have overload/charge mode. But autogun have better ammo.

I don't remember where i read it but in some book someone stated that chainsword are brutal effective weapon, better than sword because you don't need to learn swordplay or have strenght since you don't need it while using chainsword.

As for rules. Melee is seriously overpowered. You can get more hits, have talents like blademaster, counter attack and so on and mostly they have better damage and penetration than guns which is silly sometimes.

I don't remember where i read it but in some book someone stated that chainsword are brutal effective weapon, better than sword because you don't need to learn swordplay or have strenght since you don't need it while using chainsword.

Clearly they don't know what swordplay is or what it is for, nor have they thought through the idea that you don't need strength to swing fourteen pounds around accurately. Real swords are pretty good at cutting through things too, you seriously don't need to swing too hard to disembowel someone and even if they're wearing armor your sword is still a seven (or in the case of a chainsword, fourteen) pound baseball bat. What you do need is a swordarm strong enough to swing fifteen times and not be so exhausted you can't keep your guard up or swing accurately. And accuracy (and therefore swordplay) is certainly important, because no matter how powerful your blade is, you won't be doing any damage if your target isn't there when you swing, and jumping backwards when someone swings a lethal weapon at you is something that most people don't even need to be trained to do. Some of this is nerdy historical warfare stuff, but some of this is just common sense. You learn swordplay to hit your enemy at all, not to penetrate armor.

None of this really matters, because chainswords being better than regular swords in the rule of cool universe of 40k is kind of my point, but seriously. That is just the worst justification.

Re: Autoguns vs. lasguns, fair enough, I've always seen/heard it that autoguns just suck more but 40k fluff is notoriously and intentionally inconsistent so it's not a huge surprise that this isn't always the case.

Autoguns are a more versatile gun with the same damage output. Bullets are also easier to acquire with a half decent logistics network due being far cheaper to mass produce.

The real benefit of the Lasgun is that you don't need a good logistics structure. The ammo is self replenishing effectively.

If you have supply lines, the Autogun is better on every level except magazine capacity.

1.What happens to veterans when most of regiment is wiped out? In codex it's stated that sometimes two wrecked regiments are combined but what if only one or two squad remains from few regiments? Will they be combined into some kind of veteran regiment?

My interpretation is that they'd be disbanded, used for special duties or sent to act as training for another regiment, it could be you had an odds and sods company made up of the shell shocked reminants of shredded regiments (could run like a dirty dozen kind of style thing), they could also be used to act as a nucleous for a green regiment to provide some experienced troops/ncos/etc. Then again in 40k its intirely possible that if so few survived a commisar could shoot them for not dieing gloriously with the rest of their regiment...... or assign them to a penal regiment (either as guards or inmates).

2. Does Kasrkin recruit soldiers only from Cadia or sometimes from other planets? Do they act like commando unit or are frontline grenadiers like in HoTE. They are lately absent from fluff sadly.

To my knowledge the Kasrkin generally only recruit from the Cadian system and primarily from Cadia itself, however some Cadian characters are shown to be from other worlds and taken on as in system replacements (creed for example) and it is unclear if you are recruited directly from the pool of recruits into the kasrkin or if they take from the pdf and other guard regiments later, I think you would have to be in a Cadian regiment at least to be recruited if non cadian.

3. Can a normal soldier became stormtrooper or is it exclusively for schola progenium orphans?

The fluff is conflicted with some saying that they are only schola progenium, some saying that they are the best soldiers from other regiments as well (either in their own units or mixed in with the progies) and a few seeming to indicate that some units of storm troopers are raised just like other regiments but with an odd corps structure so they arn't all from the same world (those sources are very dodgy though and I tend to ignore them). There are other regiments (as people have pointed out before me) that have similar equipment and I can imagine there being commando regiments and heavy drop troopers and things which are pretty much the same equipment and even method wise but are probably less elite and less well trained. Thats my take on the fluff at least

4. If two regiments are mixed together from different homeworlds do they have unified equipment or they use same stuff from their home unit?

I would imagine they would take whatever would work together (so no weapons that conflict in calibres/charge/pack size to prevent logistical confusion) but that initially they would be differently equipped a little but that over time they would merge and form a 3rd combined identity (assuming they survive that long).

5. Are there other elite units like karskin in regiments of catachan, tallarn etc?

I would probably say no for catchan and tallarn, probably not for atilla either but possibly for Mordians, Pretorians, Vallhallans and we know for sure for Kreigers. They might have similar heavy infantry but would probably use them different. The Vallhallans also have Rangers who are mountain/special forces units (rare in the fluff but do crop up), tallarn has units based off the real world long range raiding units (that helped spawn the SAS), catchans have units that do traps and units that do heavy demolitions and carry around heavy flamers (as they can't have much heavy support in their role) and I imagine would have air cav style units as well, (well basically they are based off of Rambo mixed with Predator so you can imagine). I think Ellysians (not sure if spelt properly) have pathfinder units which go in ahead of drops but I'm not sure how they would work.

6. Does normal units beside stormtroopers and high ranking officers wear carapace armor?

Yes but not that commonly, some elite assault units, combat engineers, heavy infantry, etc (and these might be sub units of a regiment not the whole thing) would but 90% or so of guardsmen would wear flak armour.

7. Does M36 Lasgun have a full auto mode? I know that rules state they can fire semi auto only but from what i read looks like they can go full auto.

I think this is supposed to be the big trade off with las weapons they don't hit hard and they don't have particularly hight fire rates (generally) but they are ultimately reliable, reasonably accurate and you can easily carry huge amounts of ammo and replenish without much of a supply chain.

8. Does Cadian Tri-dome helmet are issued only to kasrkin?

I assume that Cadian gear is fairly widely available and is commonly copied (wether to the same standard is up to you) for guard and PDF forces especially those who have previously served alongside the Cadians.

9. While looking at IG Codex weapon list i don't see autogun. So does IG ever use autoguns?

Autoguns and Lasguns are functionally identical on the wargame level and have been for a while so its mainly a matter of fluff as to what they get called at this point. The Imperial Guard does use autoguns (and pretty much anything else really) but tends to use lasguns for ease of supply (they are very hard to break, require minimal maintanance and you can recharge the power packs through most power supplies/solar power/physically pumping a handle on a charger/boiling them/putting them in or near a fire (warning may result in them breaking/degrading ask your munitions officer for details about whether lasguns are right for you, always follow instructions)), there are plenty of instances where autoguns are used in fluff but they are generally for special purposes and used by veteran units who want the extra umph, specialists who know that ammunition isn't an issue as they will be well supplied/won't be in combat for that long but need the edge for when they are. Otherwise they are issued where lasguns are not available for what ever reason or where supply is not an issue.

10. What is imperial policy regarding equipment? In some sources it's said that troopers (mostly veterans) use weapons taken from enemy and other non standard stuff while other sources say that nobody will allow guardsman to keep equipment outside regulations.

Basically while in theatre guardsmen get more leeway if only because it is too hard to force them not to use odd equipment that they feel (rightly or wrongly) gives them an edge but when they come out of theatre I imagine they get adjusted with the more flagrent breaches of equipment being righted. Now veterans would often have more leeway as they and their officers have gone through hell together and come out of the other side and so you would probably in most regiments get a lot of things under the radar that wouldn't fly otherwise and some adjustments to equipment may become (to varying degrees of official sanction) the norm. Obviously this massively varies between regiments, salvar chem dogs don't care what you have picked up while mordians probably execute you for not fastening your shoes according to prescribed methods.

(the 2nd lot)

1. Does imperium have any other form of communication beside astropath's? I read in few novels they were using some kind of hololith communication device and nospoheric communication between planets.

Radio and laser style communication I would presume but nothing FTL apart from psykers.

2. Since my players don't get to own equipment beside standard kit (they need to return all item after every mission) i upgrade their stuff on every XP treshold. What weapons and armor should have 5k and 7,5k characters that will be proper for veterans?

I tend not to do this as I let players pick up stuff as they go and rp hiding it/keeping it/dodgily requisitioning it (or buying it off the ratlings at the motor pool who are based off Bilko but dodgier and they may cut you) but they have on occasion gotten extra equipment officially if they are doing a specific role. For my group their gear is theirs and they are responsible for it and if they should lose it then getting it through official channels is a pain in the arse (and sometimes impossible ("oh so your lasgun stopped working and you ditched it..... so you failed to maintain it properly and abandoned it to the enemy...... fill out this form to requesition a bullet, shroud and the wear and tear on my gun and the burial party's shovels, I will need that in triplicate....")) so a lot of things happen through the dodgy grey market and gaming the system.

Sorry it is so long.......