No, sorry man. but play on recruit difficulty and it is very easy and the campaign is BADASSS!!!!!! it's worth the time to beat it!!!!!
No.
nothing
If you're talking about the museum level from Modern Warfare 2, then probably not. That was a one time thing.
You can't
You must finish the game and watch the credits.
Sadly no.
At the museum... that place is unlocked when you beat the game.
There isn't one in there.
Press start and then go to leave game
press the button on the desk that says do not press
There are 4 act I act II act III and the museum
Yes you van by completing the game on any difficulty.