Yes,but I would use a memory card or something though.
Yes, but you must have a hard drive to play them. And note that you will be disconnected from Xbox Live while playing it.
No. The Only way to download demo's is to either pay for a brand new Xbox elite for 300$ and make sure it has a flash drive or you could plug a hard drive into the back of your Xbox and the file would be on your hard drive. But you could only play the demo with the hard drive in.
No.
Yes you can, but games like Halo 3 were made to work best with a hard drive.
Yes definitely as long as its on your xbox you can play it on or off xbox live.
Yes, you can. Simply remove the hard drive then insert your new one. Unless your Xbox LIVE account is on the old hard drive, then it will not affect your Xbox LIVE experience. If your account is on the old hard drive, you can move it by selecting it inside of your Storage settings, then hitting Move. After that, just choose your new hard drive and the transfer will begin.
if you have a hard drive you can play the xbox game's
Yes.
yes
Yes.
No, however you can buy the game from xbox live marketplace and the game will be on your hard drive
yes it can