Yes you can in games like halo and Call of Duty you invite your friends when you are in the lobby.If they join they are going to be on your team in the same game
Yes you do
Yes, you can play cooperatively with a buddy over Xbox live, or on the same Xbox.
Yes. The only way to play a game with a single copy is to play on the same Xbox using a splitscreen multiplayer mode (if your game supports it).
yes, you can play DLC that was downloaded on a Xbox LIVE profile and play it on a non Xbox LIVE profile
no you can only play others on the same network
no
Just hit start when it says so and then go to cooperative and make sure that you have 2 profiles that have XBOX Live. WARNING THIS DOES NOT WORK!!! =P
No, the networks and games are not connected on the same servers.
It is based on the game and what is allowed with the game. You have to choose a game that allows it if you want to play online with a friend on your Xbox 360. The same answer does apply to the Wii and PS3
no
No.
As long as both players have Xbox Live Gold you can play 2 seperate accounts on the same console on Zombies and Multiplayer.