Forget Sundance. It's not for guys like us. I hear that festival is full of insider politics, and Hollywood big-wigs. I'm still trying to figure out which festivals are the biggest that "regular Joe's" like you and me can get into. Seattle Intl.? Tribeca? SXSW? Etc.? Those are pretty big, right? I don't know, but I think regular old super-low-budget indie filmmakers like you and I can actually get into those ones.
Anyway, to answer your original question, yes, the general rule is a page per minute, but in my experience that depends on the filmmaker. I know a lot of people who say 110 pages equals 90 minutes. I've shot enough of my own writing to know that I tend to move my pages at a fast pace. I just finished typing page 107 of my first feature screenplay, and I've still got the third act ahead of me. I'm thinking my 140 pages will equal 90 minutes. Maybe it's cuz I don't write succinctly, I dunno. All I'm saying is that the general rules of thumb are just that. You can only know your own rule of thumb by writing and shooting your own stuff. So, get to it. And post it here when you've made progress. We all wanna see it.