Yeah, steer clear of Niel Simmon and Durang (especially Durang... a lot of people HATE HIM) and Tom Stoppard. He's hated as well by many.
If you're singing a song, try and get somethign a little less known and if the show opened within like... two years you may want to find something older. Some colleges want pre 1940s stuff too, so don't worry about that.
Juldo Phdal gave you some excellent questions to think over as well. They also usually ask why you like their program. There's also normally a point when you can ask THEM questions about their program, and it's good to ask a few because it makes you look like you're thinking.
Also, in your intro make sure you seem professional and confident. All you have is "Hello, my name is
and I will be performing a selection from ." and a "Thank you." at the end to show who you are, in some cases. They may also ask you to improve. My friend was asked to do the first few lines of a Shakespear soliliquy as a rapper... hahaha.