I definitely agree with your number one Casey Becker (Drew)-for the reasons you outline. I saw Scream on opening night-before hype & spoilers-I truly believed I was watching a Drew Barrymore horror film-so her shocking death so near the beginning of the film was unexpected! And the way she died-her parents nearby-so near yet so far....brutal! The only thing I'd change is your number two-it should be Tatum Riley. I loved that roller door death! It was for me unexpected-I thought she was a key character in the film too.
I don't even remember half of these. Definitely agreed with Casey, Randy & Tatum. I liked Billy's death. I'd add Anna Paquin's death from the opening of 4 and Kirby Reed's death (which I just read is a supposed death now??) oh and Jill's. Cos Emma Roberts annoys me xD Definitely going to have to rewatch all the films, and pay attention. Great list!