I can't seem to find much in the core rules that addresses firearms vs. melee weapons in combat. Obviously, at range guns win every time.

All I can find is those with fire-arms do not get the (+30)% point blank range bonus while engaged in melee. Which means if you are using an autofire firearm against someone who is trying to hit you with a chainsword, you are probably going to do far more damage to them.

Is anyone else aware of any other rules?

I believe that in Melee combat you can only use Pistols to make attacks, Basic and Heavy Weapons you don't have "room" to aim correctly and so they cannot hit.

That is correct, you can NOT use Basic or Heavy weapons while in Melee Combat. You can only use Pistol weapons, and although you get +30 to your Point Blank Range attack, you are tech fireing in to Melee Combat which means you suffer a -20 to your attack, so that puts you at +10

Actually you don't get the bonus for Point Blank Shot while in melee.

Similarly the Firing In to melee penalty is for those who are firing into melee from outside of melee (ie at range).

You may only use pistols in melee combat, it is my understanding that the reason for this is that basic and larger weaponry simply doesn't give you the space to fire. In melee with pistols you recieve -20 BS, likely because you are busy trying not to get stabbed by your opponent. The +30 for close range only applies if the target is not engaged in melee with you, or in other words you have at least 1-2 meters between you and the target (with them standing up to 3 meters away, or 1-2 squares between the two of you if you're using a map .)
That said yes, autofire is extremely powerful compared to melee weaponry however getting someone in melee typically means they can't leave melee without either A) Giving the melee'r a free attack or B) Using their entire action to disengage and thus are incapable of attacking. Not to mention most melee attacks with sufficiently potent weaponry do more than many ranged weapons with a single hit. Combine this with talents like swift or lightning attack and an off hand weapon and you've put melee nearly on part with ranged in terms of multiple hits, with each hit doing oftne more damage than the ranged (assuming the character has decent strength).

Side Note: I do believe that there is a -20 BS (the one I mentioned) when firing a pistol in melee combat seperate from that that says firing into melee (someone outside of it) would get the -20. Though I'd have to double check, usually my players just draw their melee weapon or disengage and have an ally covering fire if possible.