how do people send 问题 to the show?

I don't think 你 actually send them directly to the actors.
In the ones I have heard of, the guy conducting the interview (be it directly 狐狸 或者 any guy with a tv, radio show...) ask via his website, twitter and/or 脸谱 at his followers to send him 问题 and he choose which one he will ask.
So 你 actually have to stay tuned and send your 问题 to the right person at the right time and hope for the best.