I don't know if this is really night terrors, A.. Usually with night terrors, a child can't really communicate much at all, especially to the degree you are talking about. These sound like nightmares.
If I were you, I'd try this first. Wake him up around 11:00 pm and take him to the potty and give him a few sips of water. Don't talk to him, just quietly get him up. That breaks the deep sleep cycle. Parents with kids who really do have night terrors have used this to successfully curtail night terrors.
Perhaps, if these are really nightmares, it might help your son subconsciously to feel and know that you are still there in the middle of his night, without asking him questions, prodding at him or making him feel that he cannot control what is going on with him without you. Maybe that sounds counterintuitive, but it's worth a try.
I would not ask him what he's dreaming about anymore.
If this doesn't help, call and talk to your ped about how to deal with it. You want to make sure that you handle it right with him so that it doesn't feed on itself.
Good luck!
Dawn