Knowing basic A&P is one thing and is certainly necessary. But the question was about prepping for the class and what to focus on before taking it. My point was that the required A&P knowledge (and all the other technical aspects of EMS) will be taught from a book by an instructor. Most everyone can learn such material when presented in such a way. However, if you don't possess the three unteachable things I believe are most important to being a good EMT: care, compassion and confidence, then developing EMT skills and progressing through to becoming a paramedic will be more difficult than it would otherwise be.
Holy cow... seriously? I don't know what your exposure has been, but it sounds like you've been burned pretty bad by whatever system you've been working in. I, for one, have had some wonderful, fulfilling years in the profession.