Steam. Its a program that allows you to download PC games. If your on xbox or ps3 you have to buy it in store or in the PSN or XBL stores.
you have to download it from the download section on multiplayer you will have to download the maps 1 by 1.
Don't stink at multiplayer...
Practice
Yes. Four player split-screen local Multiplayer.
Of course. That would be ridiculous otherwise.
I dont think so, if online then no.
The multiplayer mw3 server automatically chooses you. You dont know when you are the host. It is just randomly chosen.
Simply go on multiplayer then click local and finally click split screen.
This is illegal to download a game if you don't own a copy of it. If you don't have one, you can't get a copy of MW3 or any other game. IF YOU LEGALLY OWN A COPY OF MW3, but for some reason you want to have a backup (maybe your cd is scratched), you can download it on websites like thepiratebay.se . Be aware that you won't be able to use the multiplayer mode if you do this.
under store in the multiplayer menu
No. Just Spec Ops.
You have to go onto multiplayer then go to vault.