Yes, you can! You can play a private match, which locks down the room for two players. If you are wanting to play two players on the same box, online, then no you cannot. The next best thing, is doing as many families have done, and bought two xboxes, or ps3's. Just make sure you have ample room on your router, bandwidth to support, and surge protectors.
Just go online and play a game mode... you'll be playing with multiple players.
Two players on one screen. Ten players online.
System Link
You can play online using the Nintendo Wifi Connection. It allows up to 10 players per game.
No
Special-Ops (2 players max) and Multiplayer (Up to 18 players in a single lobby)
Sixteen people tops per certain maps if you play online. Through one local system, four.
You cant
No but you can do splitscreen.
$5 a day
No, it is free to play online.
Infinity ward has not developed a way for 2 people 2 go online for any console, you can play split screen together but online no