no
Unfortunately, Onslaught was canceled due to work on Battlefield 3, as was Battlefield 1943 for PC.
No. Would be too easy to boost if they did.
Onslaught mode is available on the Xbox Live Market Place for 400 Microsoft points. There is also a in-game store that will take you right to where you can purchase the game add-on.
Yes and no, BC2 does a have a single player mode and a multiplayer mode
Yep
There is a specialization for more damage, you have to unlock it. I'm pretty sure it comes at about level/rank 17 or 18.
They're at your base when you respawn. You have to be in rush mode though.
Depends what you mean. There is a campaign mode and a Multiplayer so no its not?
It has a Campaign mode (Singleplayer) and Multiplayer.
You have to get to a level in story mode when you use the machine gun then you get it in online.
yes there is
Battlefield 3 does have Co-op mode, you can also unlock weapons for use in Multiplayer from playing Co-op.