I just got my CFI on Saturday. Everything he asked was right out of the PTS. He asked a lot about FARs, endorsements, and FOI. They were mostly in scenario based questions. I am not sure about who you are going with, but with this guy I flew with, he just wanted to see that you are an effective teacher. He let me use any notes or books that I brought for reference, and even if I didn't have to look something up, he often asked to see it anyways.

I went with a DE because our FSDO is really busy, and the oral was a fairly short 2.5 hours and the flight was around 1.1 and was very fast paced.

Good luck on your test!