you can level up da
To level up in black ops you must get kills and earn experience just like anyother call of duty games.
In Black Ops, you don't get an offline multiplayer account. It only shows your playercard from your online account. So the answer to your question is; you can't level up on your Black Ops splitscreen account because you don't get splitscreen accounts in Black Ops.
straight up SD
play multiplayer
Yes.
No, you do not.
When you rank up to level 35 you will unlock it.
of course on multiplayer
Getting a lot kills
hardcore capture the flag
level up