On the main screen you choose multiplayer then press A to sing the player in. You can play online or only with eachother.
Unfortunately, you can't change any of the settings in Black Ops multiplayer.
In Call of Duty: Black Ops, to go on multiplayer you have to go to multiplayer on the menu that says: CAMPAIGN MULTIPLAYER ZOMBIES OPTIONS
No...
Yes.
Simply go to the black ops multiplayer settings and disable the aim assist
in black ops multiplayer, everything's unlocked already.
Online Xbox 360 play is not free and the online multiplayer mode of Black Ops is the only format for multiplayer
Yes. Both modes are one game. Black Ops 2 includes a Singleplayer campaign, a Multiplayer, and Zombies!
No
You cant exactly make a gun in black ops, but you can customize a gun in multiplayer create a class mode and play online (or offline) with the customized gun.
Black-ops will have an offline version of the multiplayer, with AI opposition. Also you will be able to level up as if you were online =)
The Black Dot in CoD Black Ops means an objective or an action you can interact with.