It runs on all flavors of Windows since Windows 2000. 32-bit vs 64-bit doesn't matter to ISBoxer or Inner Space (if the game itself was 64-bit, that would matter, but it's 32-bit)

You can keep as many team configurations as you want in the ISBoxer "profile" -- I have like 15 teams defined in the same one. You can also keep as many separate profiles as you want, theyre stored as XML files