To the best of my knowledge:
1) Absolutely! EDIT: After thinking about this one, I haven't done it in GG, I was thinking about Unreal. It probably can be done, though!
2) Absolutely!
3) Not at this point in time, however, there are a lot of new Lua commands that I haven't had time to look at, so I might be wrong. Anyway, nobody has mentioned it!
4) Absolutely!
Welcome aboard!
MAME Cab PC: i7 4770@3.4Ghz (passmark 9945), 12GB RAM, Win 8.1/64, GeForce GTX645 (passmark 1898); Shiny new laptop: i7 4800MQ@2.7Ghz (passmark 8586), 16GB RAM, Win 8.1/64, GeForce GTX870M (passmark 3598); Old laptop: i5@2.3Ghz, 8GB RAM, Win 7/64, Intel 3000 graphics