Sorry for the delay!
I can't speak to what the professors in Harrisburg are like - since I was at the DE campus. However, the majority of the professor are nice and willing to answer questions. There is/was one professor that no one liked during TAP, but other than that the other professors were agreeable. Also, some professors were more interesting than others but that may also have to do with the subject of the course.
Are they accessible? That depends on the campus and the individual professors. One of the professors in DE wouldn't respond to any emails and would only talk to students in class, during office hours, or on the phone. This was unfortunate because sending an email is so much easier.
Yes, old exams are available. There are some in the library and also some of the professors give out old exams for students to review. You will take a few practice exams before the final exams.
They change the final exams so I can't give much insight into what they are like. In my opinion, last summer's exams were hard and took a lot of time to do. Also, there was so many different things you could have touched on in your answers. One exam is a memo and the other two were regular exams. In my case, the one exam was all essays while the other was multiple choice (which is actually more difficult than it may seem) and essays. After the exam is over you think of all kinds of different things that you should have or could have included in your answers.
As for study methods. That's something that each person has to figure out for themselves. In my opinion, you can't go into this with a study method set in stone. What works for one person (or even one class) won't necessarily work for another.
Hope this helps! Best of luck!