You must hit the Red Panel/Switches on the wall next to the traps only AFTER the power is turned on.
Wait till the zombies get through the barrier, then kill them. at the end of the round rebuild the barrier. it should give you 10 points for rebuilding the barrier.
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.
No
Yes, there is.
five
Yes
Yes
no
there is no other cooperative mode, only zombies
Black Ops
When you buy Revolution, the first black ops 2 map pack, it comes with a new game mode called turned, which is a gun game styled game where you play as the zombie.