I'm designing my character for our game, we play a group smugglers and mercenaries, essentially a group of semi seedy types who'll do just about anything if the price is right. Calling themselves The Inhumans, we currently consist of the following.

-Drexus - Male Chiss Smuggler/Pilot who's an ace behind the stick of a ship and also good and dealing with others. He's young, full of attitude, and has contracts working for Nar Shadaa, smuggling spice and deathsticks. He is rubbish with a blaster but has some decent ability to throw a punch, mostly from cantina brawls after saying the wrong thing to the wrong person.

-Chalryyhn - Female Wookie Marauder/Assassin. She's a young woman, deadly with her ryyk blades and quick to anger but kept in check by the rest of the crew. She served as an assassin to a Hutt for a long while but eventually won her freedom and now works as muscle for the Inhumans. She's handy with any weapon that is up-close-and-personal.

-Chabi "Doc" - Male Drall Doctor/Outlaw Tech. He is the mad scientist aboard the ship. He keeps the bodies stitched together and the tech functioning. He's loud, he's rude, he's perpetually smoking a cigar, and no one ever knows just what exactly he is working on. Doc is both a saviour and terrifying, his cybernetic arm doesn't help his personality quirks either.

-Nikkik'toth - Female Jawa Mechanic(?). She is the quiet, stoic mechanic of the ship, she keeps.everything running, she rigs new devices/weapons to the ship, and she also modifies and builds armor and weapons. She is brilliant with all things mechanical, the counter to Doc with organics.

-Ashkaylaa - Female Twi'lek Sniper(?) she's a specialist with long range sniper weaponry. Extended barrels, optics, scopes. If you need a headshot, she's the one who can do it, from far away, from stealth, and melt away before anyone knows what happened. She is on the run from a Hutt family for reasons she won't say.

-Ub'untuu - Male Rodian Pilot(?) He is our resident expert at shipboard weapons systems and tracking. He is the consumate hunter in all aspects, whether it's hunting ships through the space lanes or tracking a thief through the swamps of Naboo, he will find you, and he will blast you to pieces, or your ship atleast. Drexus' quartermaster and gunner, when not navigating.

Sooo here is where you guys come in. C-R41F, formerly a protocol droid, reprogrammed and turned into a mercenary/bounty hunter. He is a "total war" type of character, believing in using whatever weapons he needs to use to get the job done and eliminate the target as efficiently as possible. Whether than means strolling through fire with a Sidewinder Repeating Blaster and mowing down everyone in sight, or a quiet neckbreaking after infiltrating a compound, "Ralf" will get the job done. I need help on the best way to go about making a highly efficient commando-esque killer. He's gotta be well verses in all weaponry, from vibroknucklers to grenade launchers, and everything in between. Not necessarily a master of any of them, but ideally Ranged(Heavy) and Gunnery would probably see the most use. Any advice is welcome. Thanks in advance!

Soooo, all the other players look to have two specializations, so I'm guessing you're not using the standard character creation rules (not that you can't start with two specs...I am just guessing you have more starting XP to make the characters as mechanically deadly as their backstory). Anyways, here are some thoughts on how to go about it:

1. Get access to Dangerous Covenants if you don't have it...I think it is worth the money.
2. Your key characteristics are Brawn, Agility, and Cunning. Playing a droid with a specialized purpose, you should be comfortable with some characteristics at a 1 (I play an astromech droid that is the exact opposite of what you're going for). Offset your weak characteristics by investing in the most important skills tied to them (for you Cool and Vigilance as initative skills, and probably coercion and discipline).
3. You definitely want Hired Gun as your Career because it has the broadest access to combat skills, and I think the Last One Standing Signature Ability is the way to go for you (assuming you are playing RAW which says you must have the career to match the signature ability.
4. Of all the Specializations the ones with immediate access to all combat skills as career skills are Bodyguard, Heavy, and Mercenary Soldier.
5. I recommend Heavy as the starting specialization and going into Mercenary Soldier.
6. Awesome Heavy talents: Barrage, Brace, and Spare Clip at top of the tree; Heavy Hitter and Rain of Death at the bottom (of course you'll need to get the talents connected along the way to reach these).
7. Awesome Mercenary Soldier talents: Second Wind, Point Blank, and Strong Arm at the top; Natural Marksman in the middle; and Deadly Accuracy, True Aim at the bottom.
8. You might be tempted to go Marauder for melee madness or Assassin for infiltration, but I think the Wookie assassin and Twi'lek sniper might already have those roles covered. Stick to the big guns as your focus for trees, and put a few non-career XPs toward Stealth for infiltration. Work your way to those Dedication talents and that Signature Ability.

Have you thought about using this chap as inspiration?

http://starwars.wikia.com/wiki/C-3PX

Also, I like the idea of the insidious threat that a more discreet assassination droid can present; the possibility that the droid could be among its targets without them even knowing. And then, one day, its various compartments open, and their mild-mannered robot friend transforms into ED-209.

Perhaps consider that your droid is always exceedingly polite, apologetic even, about having to terminate its marks or acquire its acquisitions.

Another way to go about would be to build the character as the protocol droid first using the Colonist career with something like Politico or Performer then switch over to the Heavy specialization. Playing RAW, the Unmatched Expertise signature ability could be very deadly in combat. How would you like to make Simple gunnery checks?

As far as I know the specializations were all bought using XP. My first thought was to go Heavy and possibly go Commando from AiR but I haven't had a chance to really check out the tree it uses. Ideally I will have him using a grenade launcher as a secondary weapon and a Sidewinder as his "primary" weapon. A heavy blaster pistol and ion pistol are his sidearms.

I wouldn't mind building him initially as a Politico, but personally I would prefer to have him as combat optimal as possible.

It looks like droids are not going to be allowed as characters in this game so I've decided on making the character a Trandoshan. Fot one, I've always been a fan of the species, their religion and culture, and their enmity towards the Wookies, which will make for some awesome and entertaining roleplay. I've decided that he will actually have a Life Debt towards Chalryyhn, which will make for some very interesting interaction between the two.

With his species having changed to Trandoshan, any advice on how to make him as best as possible as a Heavy(possibly including Commando, Gadgeteer or Mercenary Soldier as a secondary/tertiary specialization(s) for him) and to utilize him as best as possible as a mercenary who brings a skill in all weapons and armor to the table. I'd like his wearing heavy armor, and carrying a small arsenal of weaponry to get the job done no matter what is throw at the crew.

It's practically impossible to take any of the Hired Gun specs and NOT be super-competent. They're all exceptionally good at what they do.

But this isn't an MMO where you have to 'min/max your DPS' or whatever you kids today say.

If you're playing a Hired Gun, you're going to automatically be great at combat, you won't have to maximize a 'build' or anything, just buy the relevant talents as you go along. Heavy/Bodyguard/Merc Soldier are all perfect for shooty types.

If anything, you might want to think about what else you can do apart from combat, because the game has plenty in it beyond shooting things. Some of this is built into the specs - Bodyguard can become a good driver, Merc Soldier has leadership capabilities, Enforcer has intimidation and underworld abilities, etc.

Finally, note that you cannot carry loads of weapons unless the GM handwaves this for some reason. Heavies have it easier to cart bulky shooters around, but the game has quite strict and realistic encumbrance limits rather than the standard videogame ability to carry 20 heavy rifles at once.

I'd recommend either the heavy for unmatched resilience and the ability to carry a lot of hardware, or the sharpshooter from AoR core book (2 copies of deadly accuracy, you could apply one to brawl) which would let you take the commando at the in career cost, or the ace:gunner from AoR, which is surprisingly good as a ground combatant (I skipped past in at first, but it's a bit like a cross between a commando and a sharpshooter, not as good as either at what they focus on but still pretty good at both), of course if you wanted you could mix sharpshooter/commando/gunner or the third one being heavy or the eventual third one being recruit wait a minute gunner saboteur would be a pretty nice combo. Or you could do heavy saboteur, the problem with a heavy is that it's not awesome at strain management and saboteur is the best at that and it's also great at grenades, or maybe a sharpshooter/commando/saboteur.

It's practically impossible to take any of the Hired Gun specs and NOT be super-competent. They're all exceptionally good at what they do.

But this isn't an MMO where you have to 'min/max your DPS' or whatever you kids today say.

If you're playing a Hired Gun, you're going to automatically be great at combat, you won't have to maximize a 'build' or anything, just buy the relevant talents as you go along. Heavy/Bodyguard/Merc Soldier are all perfect for shooty types.

If anything, you might want to think about what else you can do apart from combat, because the game has plenty in it beyond shooting things. Some of this is built into the specs - Bodyguard can become a good driver, Merc Soldier has leadership capabilities, Enforcer has intimidation and underworld abilities, etc.

Finally, note that you cannot carry loads of weapons unless the GM handwaves this for some reason. Heavies have it easier to cart bulky shooters around, but the game has quite strict and realistic encumbrance limits rather than the standard videogame ability to carry 20 heavy rifles at once.

I agree. Honestly someone with a decent Agility and some relevant skills, along with a modded weapon will be able to annihilate 99% of the opposition without too much trouble. Personally I think something like saboteur and engineer will be a lot tougher character who can still hand out a ton of damage but also be able to contribute in a lot of other ways to a group. The first three tiers of those two trees turn you into a strain master.

Outside of combat I would ideally like him to go the route of intimidation and "terror tactics" in a way. Our Wookie is more of the cuddly sort despite being an assassin, and the sniper is the silent, leave the group and take the shot kind of character, so my character would be best in the role of being the "legbreaker" and scaring others into giving us what we want. I'd really also like for him to have decent skill as a starfighter pilot and also be decently skilled as infiltration(this should probably include slicing?), stealth, and demolitions.

You understand you basically want him to be everything which is going to take a lot of xp and time. In that case I would stop laboring over the exact ideal initial build because you're going to drive yourself crazy and just make something you like to start. Any of the Hired Gun or Bounty Hunter specs will give you a solid base to start.

What 2P51 said.

Guns, Coercion, Piloting, Stealth, Slicing, Demolitions?

That's at least half a dozen cross-class specialisations right there.

Build a thematic character that doesn't tread on the toes of other PCs.

Ahhh true enough haha

I'll stick to him being guns, coercion, and demolitions.

Dangerous Covenants has you covered, then.

Heavy

Enforcer

Demolitionist

All are in same career.

I like the idea of an Aqualish (Walrusman, as some of us once called him). We have a merc build of Hired Gun: Mercenary and Enforcer. He's and intimidating with field leadership to help the group. A great group leader build.

What 2P51 said.

Guns, Coercion, Piloting, Stealth, Slicing, Demolitions?

That's at least half a dozen cross-class specialisations right there.

Build a thematic character that doesn't tread on the toes of other PCs.