Is it fine to ask who are the search committee?
In general, I would recommend against asking who the search committee is. It might give the impression that you are trying to "game the system" rather than simply put your best foot forward for everyone. That said, I don't think this is a serious faux pas.

Some departments, including my own, post a list of committee assignments on their department homepages -- mostly out of convenience for their own faculty. So you might be able to answer your question without asking.