I've started using some of these questions, especially the meta questions. They really do elicit some interesting and revealing answers.
At an interview this last week I got asked a difficult question by the candidate. I was reasonably sure that I wanted him in my team. After he asked that one question, I was certain that I wanted him on my team. One of our Four C's is Curiosity.
We had been discussing the range of languages on his CV. Then I gave him an overview of the technologies we use including that we use native Javascript instead of frameworks. He questioned why that was...