You hack it
There is no limit to levels on Zombie Mode in Black Ops. It is a survival type game mode and does not end except when you die. There could not be a number of levels because it is infinite with new levels continuing until the game ends when you die.
It does have a zombie mode and it is really fun.
(sadly) there is no zombie mode in CoD 4. the only zombie modes (so far) is the sombie mode in world at war and the zombie mode in black ops.
I highly doubt it but nobody has made it past round 150 very many times.
No
Yes, there is.
Yes
five
no
Yes
there is no other cooperative mode, only zombies
Black Ops