Quite an impressive list of questions to ask front-end developers. I don't advocate focusing so heavily on questions such as this that you fail to ask any questions about soft skills, creative thinking, working with UI designers and back-end devs, and so on — all of which are essential to front-end development in my experience. But it seems like a nice list to select some questions from nonetheless.
"Can you describe the difference between progressive enhancement and graceful degredation? Bonus points for the answer 'no one can'."