Having been through a few orals, like what was said before...they'll use the overhead panel as their oral guide for systems. So my advice is to know the electrical system COLD, because that's the first panel they'll most likely start at. Set the tone early, and you'll be fine. IAC items...never been asked anything except Aileron/elevator system jammed, stab trim runaway, or uncommanded yaw. They'll ask you questions that they don't expect you to answer correctly, as teaching points. Don't let it get you flustered, no one is perfect.