Now, I don't want to sound like an old grump or anything, but asking everyone for the answers will not help you at the interview. If you learn the answers to scenarios, the interviewer WILL pick it up. I know that you are just looking for help on here, and I applaud that, but the purpose of a recruitemnt interview is to look for potential, not for someone who knows all the answers... Although I have not conducted ATCO boards, i have interviewed literally hundreds of candidates for NATS.
As to your visits, ask anything YOU don't understand, ask what the particular "challenges" of THAT airfield are...
Hope this helps!!!