Congrats on moving on up, Julie!! I'll probably repeat what some of the other people said, but oh well.
1) The difference between the two is confusing and had to be explained to me about 17 times and I still don't know if I understand it.
I think it has to do with your generals being science based. If a certain number of your gen. eds. are science based, you'll have an AAS degree.
2) I don't remember about the enrollment process since it was eons ago that I did all of that. But like Delynn said, you can start taking a couple of the NC exams before you're even enrolled. In fact, it's smart to do that, since once you're enrolled the clock starts ticking, and for every 365 days that you are enrolled, you have to pay a re-enrollment fee. So take what you can (those couple of NC exams and your gen eds) before enrolled, if possible.
3) I've seen people whip through it in 6 months, taking a test a month and then onto their CPNE, and I've seen people take years. Kind of depends on the person and what else they have going on in their lives. I got pregnant exactly one month after starting the program. Between nausea then having a new creature that smelled like baby powder invade my home, working FT, and periods of lack of motivation, the entire thing from start to NCLEX took me 3 years. My biggest piece of advice is once you get going, don't stop for long. It's very hard to come back from long study breaks. Take a little time off here and there because you'll need it, but get to know yourself and know how much time is too much to take off.
4) Yep yep, you can do your CPNE (clinical exam) at any of the sites in the country. Throughout your studies, make good use of the message boards (this one, Yahoo, etc.) and keep your eyes open for what people had to say about the different CPNE sites. Even e-mail people who have tested and see what they have to say about their site. That's what I did, and that's how I decided on what site to go to.
Best of luck to you!!!!