NICE! Congrats!
I am still learning the ins and outs of my 360, so I wont be much help. But I will give my 2 cents.
1- That I do not know 
2- Yes, its VERY easy. I just did mine last night. 20g on Ebay for 27 bucks.
3- Still learnin here. I really hate the interface.
4- Yes, Play and charge kit. Rechargable battery with USB cable, very handy.
5- Still learning that too. Not much different than PSN, so far.
6- Silver and Gold. Every game I tried to play online required me to upgrade to Gold. Silver seems to be only for downloading demos etc.
7- Gears of War, Crackdown are the 2 reasons I jumped into the XBOX. I have my eye on Tales of Vesperia and Infinite Undiscovery and will pick those up soon.
Sorry if I wasnt much help, but Im just a baby Xbot at the moment.
Again, GRATS on both HD systems. Life is good!!!
Tifa got MOVES!
