yes u can
Sixteen people tops per certain maps if you play online. Through one local system, four.
System Link
Depends which modern warfare game you mean if its the first one you cant play co-op but on modern warfare 2 you can play with another person but only on special ops. You will need to get a second controller, use system link or play with people online(Xbox live/PSN).
You get a friend that bought them and then you get there online account info and then you just download it on to your system
not on the same system but with other people.
Firstly, Modern Warfare 2 is not "om" and any system. However to answer you're intended question, the answer is no.
yes it is in the multiplayer mode
playstation 3
If you mean in the campaign, then I do not think so. In online multiplayer, you can set your family settings so no one can talk to you except friends. How to do that depends on what system you have.
System link is when you connect your and somebody else's console and play a match
7.5 million just for the Xbox 360 system and almost another 5 million for the PS3
Ill have to say Atari