All you have to do to change profiles is log out of the profile you automatically sign into and when you exit press the silver button and press the sign in section and then choose the profile you want :-)
Yes, XBOX live Silver comes free with you're xbox 360, altough you're are going to need a internet connection.
If you have a Xbox live Gamer profile, you can just recover it on the new Xbox. If you are not online, you will need to buy a transfer cable.
If you have NXE you can take pictures of your avatar. Or, regardless of your dashboard, new pictures can be purchased on the Xbox Marketplace.
First, you must have xbox live. Go to your sign in screen and at the end on the list there should be an option titled "Recover Gamertag". Alternatively, you can press the xbox button on your controller and there should be on option, second from the bottom also titled "Recover Gamertag".
If your asking if an old 360 Hard drive will fit in a new 360, no. Look at the pictures, dude. One goes on the outside, one goes on the inside.
yes they can on another or new xbox 360
when it goes onto a silver membership you can go to the shop and buy a gold membership or start a new profile but you can't bring your gamer-score over
New games do work on an Xbox 360. This is, of course, as long as they are specifically Xbox 360 games.
No you have to make a new gamer profile and then do on that one the reason because Sega was rushed and it was not fully fixed of everything
yes
If you are referring to an "older xbox" as the regular xbox, then the answer is no. but if you are referring it as the first models of the xbox 360, then you can play halo 3 or any new xbox 360 games on your Xbox 360.
Of course the original Xbox 360 games are no different from the new Xbox 30 slim games.