My experience is pretty much what the others have said. My curriculum is systems-based after the first block (~ 8 weeks of basic sciences). Our PPC/OMM course is not only where we learn osteopathic diagnosis and treatment, but also where we go over the standard physical exams (neuro, cardio, etc) so there is some overlap with our clinical medicine course there which is nice. I would think it would be impossible to make the entire course coincide with your first two years, so do expect some amount of time to be studying information that doesn't correlate with your other courses (I.E. Sacral/Pelvic diagnosis during neuro block.)
Everyone is always worried about the "shorts, or shorts/sports bra" rule - but think about it this way: you see more skin at the pool or beach than you do in PPC/OMM class. You'll also get over putting your hands on people pretty quick, so it's probably not worth it to start laying hands on every person you pass at the mall.
Really, as long as you aren't a creeper you'll be fine.