Candidate questions are part of mutual evaluation. Ask about real responsibilities, success measures, team practices, current challenges, decision authority, feedback, and growth. Research facts that are publicly available, then use interview time for context only people inside the role can provide.
A strong close can summarize one or two reasons the role fits, express informed interest, address any unresolved concern briefly, and confirm the next step. A follow-up message should be specific and concise: thank the interviewer, mention one meaningful point, reinforce fit, and avoid pressuring them outside the agreed timeline.