I found a really good site from my local film office where a lot of independent and student projects are posted. The site has been a big help so far, and I've gotten several legit jobs and auditions from them, but I'm having some trouble regarding a student film. I've never been involved in a student project before, so the details are a little unclear and the director has no company or site for me to research. Is there a way I can find out if he himself is legit, and are there any questions I should make sure to ask him before committing to his project? (Any other input regarding student films would be helpful also!)
Thanks!

You could check with the school to be sure he is actually a student.

That's good advice. If he is a student, you could also contact somebody who teaches there and ask for an opinion. Then, make sure you talk with the director (not just e-mail) and ask a ton of questions...try to get details about where you'll have to be, what you'll be doing, who else is involved, time commitment, how they plan to distribute the project, etc.etc. If there is money involved, get it in writing because a lot of student projects are based on the hope that people will get paid, but often the money just isn't there when payday comes around. If the director is willing to answer all these questions and you're satisfied, it's probably ok to go ahead with it.

One obvious point comes to mind: I can barely recall ever auditioning for a student film elsewhere than on the school's premises.

Even then, the film itself might be shot in a dicey location, or, alternatively, the filmmaker might quite innocently choose to have auditions elsewhere. But if you're concerned, the first step might be not to go to any auditions that aren't actually held at the school in question.

All the student films that I auditioned for, were at the school or at another theatre's performance building.

One exception to this might be in schools near a major acting hub--for example, students in Orange County might drive up to hold auditions in LA...

Along with the great questions listed by others, especially talking to the teacher of the class, you can ask the students where the project will screen (if its for school it will screen either in class or a school screening venue) and where it will rehearse and shoot. If the auditions are on school property or at a legitimate studio rental site, you will get a lot of clarity just by meeting the students in person!