I of course second/third/whatever this sentiment. I was moaning about the lack of new, or even good BT games until my friend directed me here around christmas. It's wonderful that people would give up so much of their time for free to make something like this! I didn't know but now that I think about it I can see why we wouldn't be able to give money (license reasons) - can someone confirm this? Are there guidelines for what is allowed?
matter of fact, this game has me so attached i drug out the heatset and am currently looking for a cheap joystick to use, unless the 360 wired controller will work, then i may pick up one of those and use it with the keyboard
I am basically certain that a 360 controller will work, I can successfully use a ps3 controller via drivers that emulate an xbox controller for this game (crysis only allows certain gamepads, xbox is allowed, ps3 isn't). As for a decent actionmap, can't help there sorry, realised after a short time that mouse and kb work better for me.
Now, just add an overarching universe campaign with the Houses and individual stats/C-bill accounts/Mech bays/inventory and it'll be perfect! 
I've got some big ideas on this myself along these lines. I've been dreaming for a couple of years about a BT game where you could play as IS, clans or mercenaries (actually only thought about mercenaries first, but realised you'd have to have someone to work for, not AI) and have individual characters, merc outfits, contracts, c-bills, salvage, personal machines and a proper real-time universe. Basically what you said!
You could even market it as an MMO since publishers seem to be obsessed with them (would make it easier for someone to fund it). I'd hate to have to pay a subscription though.