I'll try to answer your questions, but I don't have and have never played a 360.
1. It doesn't have an interface like xbox live, and to date there are no MP games for it. However there WILL be (first one comes out in Jan or Feb), but even then, I think you have to have someone on your contact list to play online with them. I could be wrong here. Someone with a 360 can probably answer this better to your liking.
3. There's a few out now: Red Steel, COD3, Far Cry. I personally haven't played any of them, and I've heard reviews go both ways about them. So I guess the only way to tell would be for you to rent/play them yourself. To each his own. I personally am extremely looking forward to metroid, which I'm sure will be kick ass.
4. Not really, and its a wicked controller once you do get used to it. I love the thing.
5. Zelda:TP of course, Wii Sports is actually awesome for multi-player when you have friends/family over. Super Monkey Ball is sweet. Those are the only one's I've played, but I'm sure more people will chime in on this one.
I personally went with the Wii for these reasons:
*The controller, and more importantly the POTENTIAL for the controller. I can only imagine the types of games that are going to come out. And FPS will kick ass with this setup.
*It actually requires you to DO something while playing. So it's good for staying in shape too =)
*The price of course.
*Virtual Console...though I'm still waiting for the best games to be released.
*To me, I see the xbox360 and ps3 as just graphical upgrades to their predecessors. Sure, they have a few more features, but I was looking for a pure gaiming system, and gameplay-wise, they brought nothing new to the table.