Jessica is right on the money. I would highly recommend taking one of the two courses you can take before you enroll. That way you can see if the program is for you without losing the enrollment fee. Something to keep in mind though is that you might want to enroll before October because there are several changes regarding how many ACE credits you can get and if you will have to retake Micro and A&P if it has been more than 5 years since you last had it.
How hard are the exams?
They are challenging but the content guides are very detailed and do an excellent job in telling you where to focus.
Have you failed any exams?
No, but I did get a C on LS3; trying to beat that September deadline for the FCCA (which I did, hooray!)
Do you really need all the books?
There were a few that I felt I could have done without. Fundamentals and Med Surg are a must in my opinion. Maternity for repo of course, but I barely cracked it for the other subjects. I strictly studied Med Surg for all the Life Spans. You can get your books really cheap from Amazon
Any tips for studying or testing?
Can't think of anything specific. Just use your content guides!
Is it really expensive?
Compared to most schools, not so much. The convenience was really worth it for me. There are also ways to save money (use CLEP for prereqs, take Information Literacy through Penn Foster, buy your books used and buy the previous editions, etc).
Also do you think it would be possible to do an Exam a month?
I KNOW it would be. I did all non-Life Span courses in about two weeks each. I did take about a month for the Life Spans though.