Questions on Upgrading from Tiger to Leopard

Hey guys,

I switched to a mac almost one year ago (bought my Macbook last August) and at the time I didn't think it would be worth waiting for Leopard to come out because I figured it would be pretty buggy at first. Now that a couple updates have come out for it and it seems to be pretty stable, is it worth upgrading? A couple of the features I'm interested in are Time Machine and Spaces. Also, I like the overall feel of Leopard more (I have a friend who has it). I still have a couple of questions though:

Is it worth the $116? I've seen it on eBay for less but it seems kind of sketchy, like the software may be tampered with, even if they say it's still factory sealed.

Should I get iLife '08 as well? Reading about the new features hasn't really blown me away, but I'd like to see what people who have actually used it think.

Can Time Machine use MobileMe's 20 GB of online storage to backup files? I ask because I am considering getting MobileMe as well, and I think that would def. be a huge selling point for me if it can.

Will I lose all my files (iTunes, iPhoto library, documents, addresses, etc.) when I upgrade? Do I need to take my Macbook to the Apple store to have them make the transition there?

Would I be better off waiting and buying a whole new computer when Snow Leopard comes out in a year?

Any advice on whether or not it is worth switching would really be appreciated. I'm on the fence on this one.

Thanks so much!

 

Thanks Xavier, that was very helpful!