You're right about the format. The first day is 400 questions from randam sections (i.e. pharm, perio, endo, etc.). It goes from 8:30 to 4 P.M. The second day is only a half day. Its 100 case-based questions.
I was looking at the question breakdown for the part 2 exam. There's 30 endo, 45 operative, about 35 pharm, about 55 ortho/pedo, about 50 behavioral science, 45 perio, 45 prostho, 45 oral path questions.
Good luck studying guys.