A very important question the player should ask themselves: "If I were NOT playing softball, would I want to attend this university?"
Joe touched on an important viewpoint, which I would describe this way: "Ask not what the softball program/university can offer you, but what YOU can offer the softball program/university".
Joe's right about finding most answers on the university's web site. Lots of other questions are covered under NCAA/NIAA rules. IMO, although playing time questions may be a valid concern, I'd avoid those like the plague - unless you want to give the impression of entitlement. Never a good impression on a coach.
I'd suggest questions about academic support opportunities - "If my DD falls behind in a certain class, what help is available for her?" Nearly all freshman are required to attend study tables until they can prove to the coach that they can maintain a solid grade point average.
What I found from visits was that with all the assistance nearly every university provides scholarship athletes, the student has to TRY to fail! After all, it's in the coaches best interest to keep the student-athletes eligible. We talked very little about softball in three of our visits with coaches. Most of our conversations were about course offerings, facilities, school surroundings, part-time job opportunities, etc.