LOL Mullenix. I have many thoughts on her.
If your class is anything like mine, she'll try to freak you out the first day. She calls up two unsuspecting 1Ls who are already anxious about their first day of law school and makes them do some kind of intake interview with her. I think the point is supposed to be that when you're interviewing a new client, all you need is facts, so if you're one of the unlucky ones, just keep focused on the facts and don't pretend you're already familiar with civ pro concepts like personal jurisdiction, subject matter jurisdiction, or whatever else you might have heard of. Of course the real point is to intimidate everyone, teach everyone that they don't know anything, and set the hard-ass tone for the rest of the class. (My year, a guy had a seizure while she was berating him.)
She does a system where everyone is assigned one or two cases to cover in extreme depth and basically gives you license to ignore the rest. You have to figure out a way to motivate yourself to do the other reading. Start using the Glannon Guide and the E&E right away to learn the basic concepts, then read the cases (and focus on the facts when you get called on!). Her casebook is kind of useless for learning, since it contains only cases and statutes, no explanation or background.
She doesn't release any model exams; she makes you buy them. I do not understand what the point of a multiple choice civ pro test is, but she clings to it. It's an absurdly hard test, and the curve is brutal (I think I heard my year that the difference between an A- and a B was like 3 questions). I think my main mistake in that class was not relying on supplements from Day 1, and focusing too much on my own assigned cases (for which I was on call for three days) and subordinating everything else. Your mentors will keep you up to date on what she's been doing with her classes and exams since I had her in 2010, and they might have outlines as well. Remember, all that matters is the exam, not how many facts you remember from your assigned cases. You're going to feel like shit at some point, but don't let it distract you from the real goal -- and remember, she does it to everyone.
Believe it or not, she's a very nice person in real life, but while you're in her class, she has her persona and sticks to it. I encourage you to go say hi to her after your semester is over.
As for the others, I've not had them (except Einhorn). Chesney seems to be very popular and student-friendly. Franklin is a hard-core feminist scholar who's married to Fishkin, who is awesome. I'd guess she'll be a very liberal con law prof (equal protection, due process, etc.). I think this is her first year teaching con law, yes?
Books: I've never had a problem renting from Amazon, but if the policies say you can't underline, I wouldn't bother. If you can find them used, great, but Amazon tends to have better deals across the board. I know some people who went to extreme lengths never to pay for books, but this seemed like a waste of time that could be spent studying. Keep in mind that if you have to buy new (from anywhere), the co-op will often buy them back at good prices, in cash.