Buy it, Download steam +updates and tada, go to town.
yes you can
....install it. Set up controls. Play. Easy as that.
No because they are both different formats
No
Yes, a keyboard is necessary to play Modern Warfare 2 on PC, however you cannot use a keyboard to play Modern Warfare 2 on PlayStation 3 nor Xbox 360.
It not a part of Call of Duty Modern Warfare 2
Not really. The campaign will still not make sense, even if you played the first Modern Warfare.
no
computer, ps3 or xbox360
No, you must buy the game disk that is made for your computer
yes because I have a friend who has it on his computer
No they are two diffrent games.