I agree, they do a really poor job giving you enough information to prepare for this exam.
I just took it Weds - you get 7 hours, with two 15 min breaks. I finished the first section with a half hour to spare and the last section with about a hour to spare. The middle section I finished just about on time. There were a few more questions in each section than is listed in the manual. I think the manual says 100, 80, 100 where the actual test was 105-ish, 84-ish, and 115. I'm not sure if the extra questions are "experimental questions" (doubt it considering the quality of the exam, see below) or just thrown in there to make each question worth fewer points. I would review a lot of oral path, radiology, perio, and dentures. There are a few other threads here that go a little more specific topic wise, so I'll leave you to find those on your own. Be prepared for poor grammar, spelling mistakes, bad answer choices, and poor quality clinical pictures and radiology. In most cases you can narrow down the answers to only one or two possibilities based on the other answers/question, sometimes you just had to guess. It's a really disappointing test in terms of professional presentation, but I really wasn't expecting NERB to be anything more than a money grabbing old school organization. Honestly, it would be embarrassing to show this exam to other health professions and tell them that this is part of what is between us and being able to practice in most of the country. I guess I'll get my grade in January - I don't care what I get as long as I don't have to shell out another 990$ to take this exam again. /End Rant.
Oh, and Good luck! : o )