I think you have to wait until after you are rejected (if you are) to find out how you did on an interview. It wouldn't seem right to ask previuos to that---your application is still under consideration.
I am not totally sure what you mean by any red flags in your application but I would assume that you are talking about if there is anything looked upon unfavorably. This also, I would assume, you should only ask after (if you have been) rejected.
Pretty much if you get in---yipee who cares if there were any problems.
If you are rejected--call after and ask what would be the nest way to improve your application/ what are your weak points.