CJ,
I have a Mac, and I am sure you will love it. As a matter of fact, I have a PowerBook -- what a GREAT machine that is. I have "switched" my entire family to Macs (including the CEO), and now we have three Macs and four iPods!
To answer your questions:
1. Just copy all your files onto a CD and copy them onto your Mac. If you buy your PC at an Apple store (which I recommend you do, by the way), they will actually transfer any files from your PC to your Mac at no charge. The pride themselves in their customer service, and they will gladly help you switch.
2. The Mac OS (OS X -- pronounced OS ten) is elegant, secure, and very easy to use. It will take you a whopping two minutes to learn it. The ONLY thing I recommend is to buy a two-button mouse, which is fully suppored by OS X; Apple, however, only gives you a one-button mouse. Again, your local Apple store will gladly teach you how to do anything you need to do.
3. You will have to buy Mac versions of whatever software you use (MS Office, for example). Tell them you're a student, and you can buy it all at a discount.
MacTeens.com is a great web site for, well... teens who use Macs. Both my sons visit that site often, and I often hear, "hey, dad, I was reading in Mac Teens..."
By the way, ensure that you get AT LEAST 512MB of RAM with your PB. OS X is a wonderful OS, but it likes memory. 1GB would even be better.
If you have any problems, or questions, feel free to PM me or email me. I can help you out.
Juan