When they ask you “Do you have any questions for us?” they are saying “This interview is over. Whatever we say next will be a kind of dummy question-and-answer thing, not part of the interview proper.” So DON'T become all heavy and serious at that point. There are stock questions you ask that perform “Hi, I know this is the end, you've been great and it's been a proper interview”—like “Can you tell me more about your students?” or “What opportunities are there for interdisciplinary scholarship and teaching?”
DON'T use the time as an opportunity to prove yourself once again.
NEVER, EVER ask them anything personal AT ALL. ALL those sorts of questions ignore the rule that there is an unspoken signal that the interview is over. Questions about departmental vibes, politics, money and pensions are FORBIDDEN. As are questions about “What happens next?” “Will you call me?” “How did I do?” Swallow hard. Smile. Exit. Let there be space.