Just remember that the show is live, and Arizona doesn't practice light-saving time. All questions should relate to the topic of the day. I bet he has a few secrets we would all want to know, like the secret of his success. I read an article about his writing habits in Writer's Digest recently. The man is an incredibly prolific writing machine.
Many authors are afraid of live interviews.
It's a lot easier than pitching your book to an agent or an editor, on the phone or at a conference. The secret is to be prepared. I usually email the questions in advance to my guests, so they can think about their answers, write notes. We meet at the studio one hour before the show to go over all the details, relax, establish trust. The better they sound, the better it is for the show.