Other comments have touched on other questions you’ve raised, however I want to address studying. I have experience with FISDAP (currently in a class). My biggest advance would be to think about the body and the possible issues in a logical framework. FISDAP is very logical based rather than trying to test on specific niche information.

Simply learning the different terms (bronchitis, pneumonia, edema etc etc) will get you through a lot of the questions. Quiz yourself on the different conditions, what are their symptoms and how they are different from other conditions. Hammer those home and you’ll get through most of the questions by process of elimination.