yes u can
Chat with our AI personalities
I don't think you can, but you can exit combat training and start it again.
50. There is not Prestiging.
from the main menu choose multi-player then xbox live or playstation network (depends on which system you have) then choose combat training
You got to play combat training and have your friend sign in with a different controller
There is no bot mode in Call of Duty 4, so the only bots are in campaign. In black ops there is "Combat Training" which puts you against bots in multiplayer matches.