Not so much questions but opinions, yes. I can be very opinionated at times and have posted rather controversial posts on certain types of questions. I don't regret sharing my viewpoint but a lot of people (especially on here) do not like when anyone says anything that differs from their view. These posts I made just stirred up a lot of drama and ended up with people insulting me or name-calling and I don't like that sort of thing so I just don't really post on controversial questions anymore for that reason.
Yes I have regretted posting some opinions. Because some people here misunderstood and started downvoting or arguing with me, without realizing what I was talking about. And there are some people here who just like to downvote even if I am saying I like bunnies, or that I don't like my look, or that I hate the words yolo and swag. I mean what the hell? It's my opinion, doesn't have to be yours too. But in the end, since we can't delete them, I just try not to care. People will always have something to say, it just depends if you really want to listen to their comments.
Yeah, I have wished this myself. I, along with other people, ask innocent questions or we honestly do not know something and somebody chews us out over it. It's happened to me and I've seen it a lot as well.
I have regretted posting some questions before because people misunderstood them and exploded. Now that I think of it, that's the same reason I've regretted opinions. I've also regretted sharing some things about myself.
Quite often, you are not able to phrase a question to mean what you actually wanted; and it ends up creating this big uproar and typical GAGville responses as if you have committed a sin asking that question.