Nope.
you cant play against people on other systems. the console makers wont agree to share servers and players (customers)
yes you can
No, you can do offline solo/split screen or online with three other players.
I'd say Call of Duty 3 because there is no online mode so he won't be harassed by other players. Also the language won't be as offensive in the regular game as it would be online with other people talking to him.
4 players
A server allows the game to be played online with other real players.
offline:4 players online:50 players
Up to 4 players locally and up to 24 players online
If you mean people on different consoles...... nope..... !?!
No.
No
i believe 367458,7858695846795,984756843567.