No you can not unlock the zombie levels by playing co-op you can only do it by playing single player. Also if you play certain level in campaign you will unlock levels for Zombies.
no
no
you cant nazi zombies is only for ps3 xbox 360 and PC
You can not the game does not have it
iam pretty sure u can
complete the campaign then you will unlock it
Yes you can unlock things on it you just have to find them.
You need to complete the campaign and then you will unlock zombies>
by beating the game
Their isn;t Nazi Zombies for Cod4 but for Cod5 yes, and their isn;t a unlock cheat. Just beat the campaign.
To play Nazi Zombies you must have Call of Duty: World at War & have either an Xbox 360, PC or a PlayStation 3 (it's not in the Wii version of the game). To unlock it you have to complete campaign/story mode or you can unlock it playing online.
if you have an xbox360 you have to sing up to xbox live.