I took the OAT last October, and the answers were not in the same order as the text. If I were you, I wouldn't study MCAT Reading passages to study for the OAT. I've taken both tests, and the types of questions asked on the two are very different. The MCAT questions are ask more about deeper understanding, while the OAT questions ask more about very general understanding, and a bit of identifying details from the passage. Many people have said (and I agree with them) that, if you can read reasonably quickly and English is your first language, you should do quite well on the reading comprehension portion of the OAT.