What are some of the best questions to ask a prospective adviser?

[InquilineKea]

That could determine the chances of fit, or of possible future conflict?

I'm a bit of an unconventional student, so this is going to be important for me.

[far_to_go]

You should try to figure out if they plan on retiring/moving/quitting within the next few years (this needs to be phrased delicately).

I asked a few people "What are the qualities that enable grad students to do well in this department/as your students?" The answers can be very telling.

[rising_star]

There are tons of past posts on exactly this topic. Check here and in "Interviews and Visits". But really, we can't tell you what the most important or "best" questions are, particularly given your non-traditional background. You have to figure out what it is that you want and/or need to know, ask questions to elicit that information, then figure out what to do.