Whew! What a lot of things to answer...
(I hope I'll cover everything)
Firstly, yes, that book is indeed a crazy thing, I do love it though. Pages of glossy pictures of art...ahhh.
Luckily, I just got mine from my university's bookstore. It was required reading for my western art history course. That's pretty impressive that you've bought the book just for an optional course though! However, it is definately is a good investment and if do decide to continue in art, it'll be useful later on. What next?...let's see... Oh, well, I haven't bothered to carry mine around. My university's an hour each way so it'd be a horrible schlep to drag that book around. Most people in the course just leave it at home and study from there. Also, you could always just photocopy individual readings, which are definately much lighter!
I'm not sure what an AP exam is though, although I will do my best to help you. I actually just finished writing my final exams this week so I'm in still in exam mode as well. As for the teacher being away thing I'd just focus on studying on my own. Nevermind their deliquency and just worry about yourself. Honestly, this is for you, so you're going to have to be the one to take care that you get things done. Make sure that you do all the readings and try to take notes, because they can actually help you to remember. Another thing that I like to do in art history is to add little drawings at the sides of my notes. I'm assuming that you're a visual person, like me, and it can really be pretty useful. Especially in architecture, where you'll need to label all the different sections of the building. Another general tip is to just talk to someone about what you're studying. I read this somewhere and it's been really perfect for me. Just pretend that you're teaching a class and that you have to get your message across to your audience. I find that when I'm talking I tend to become more relaxed and remember a lot more than I thought I even knew. Also, I do this particially for pleasure (I'm a nerd, I know!), but also because it really gets things fixed in my mind: spend some time each day browsing just art history sites and books to get yourself in the mood. You'll learn to recognize a lot of the images and will also pick up a bunch of the general terminology. Also, this is kind of silly, but I sometimes like to listen to period music while I'm working. Okay, that's about all that I can think of at the moment, best of luck!
Oh, I'm not sure which movements you've been studying, but I've found these sites really helpful...
http://harpy.uccs.edu/greek/greek.html (Made with an educational purpose, good images and accurate)
http://gallery.euroweb.hu/artist.html (This site is amazing- I actually go here for fun sometimes...
)
http://www.abcgallery.com/ (Loads of artists and paintings)
http://www.christusrex.org/ (It is a Christian site, but they have
the most fantastic art collection!)
I love to read/study Art History (second edition) by Marilyn Stockstad (1200 pages to study! yipes!), but I reeeeally want to read a novel. 
The heaviness makes it especially hard to study because it's so hard to carry around (and it's awkward to hold). I felt so silly trying to bring it to the beach this summer that I just had to give up. 
