How old are these kids? I was sort of confused. They're in high school, but 14 can be different from 18, especially when you having them having sex and getting drunk.
You spend a lot of time with this kid waking up. The whole hitting the alarm clock and waking up to a messy room with some kid with untidy hair is way too cliche. Half the scripts on this site begin like that. I'd find some other way to do it. I guess you should ask yourself, what's important about that scene, and what details can be shown later?
You introduce way too many characters in the cafeteria. It's daunting. There was so many, I made a mental note not to remember any of them. You give vivid descriptions of each of the "cool" kids, but it ultimately doesn't matter because you kill them all in the following scenes. When you give them such length descriptions, it makes me think they're important, but they all die very quickly. And their descriptions are overkill. You introduce Jan, Trish, Luke, Bill, and Marcie ALL as begin athletic, fashionable, and self-important. First, it makes it seem that none of them have any actual character, but more importantly you don't need to tell us that five different times. You can fit it into one line: "Brett sits down at another dining table with another group of *fashionably dressed athletic kids, JAN, TRISH, LUKE, and BILL*." (11).
If they watch so many horror movies, why don't they imagine that he'll have super powers/super strength like most horror villains? They seem pretty confident that beating him with a couple of rucksacks will get the job done. And it's surprising that it does get the job done. Edgar doesn't seem to be a remote threat. I'd think you want your villain to be somewhat menacing.
I think here's the big problem. You kill a bunch of throwaway characters (David and Claire) in the beginning, but then you repeat yourself and kill more filler characters (Jan, Luke, Marcie, Bill, Trish). It's repeating itself and takes away from the excitement of the killing. Killing characters isn't exciting or suspenseful if we don't know them, and doing it twice is too much. You should find a way to combine them into one scene. Or just take out the first scene altogether. Now, you may be thinking, the first scene is there to hook the viewer. You can't take it out, because if you don't start with Edgar, the alternative is starting with Russell waking up and having cliche banter with his cliche family. But now we're go back to the original problem of that alarm clock scene. You know you don't want to start with Russell waking up because it's a boring beginning, but you also don't want to kill seven boring characters in the first thirty minutes (too much too fast). So my solution is this: ditch the intro, ditch Russell waking up, and start either at the cafeteria or at the camp. Or come up with a better introduction. You know that scene in Scream where they're analyzing the horror film at the party? Maybe start with something like that. It'll introduce your characters, the idea of horror films, and it can be something they all do together after their first day training to be counselors.
Best luck, and remember, I don't know what I'm talking about so take my advice carefully.