To apply for a school I'd say this looks pretty good. It's more than I ever did to get into my animation course. Though to be fair, my school wasn't based in the US so there might be difference in criteria here.
I find it difficult to answer, I don't know what the school is looking for in their students. Personally I'd say having good drawing skills and a passion for animation should be enough, both of which you seem to have. But if they're looking for actual an actual animation portfolio, then yeah, I'd go with model sheets and a few character animations. Perhaps you could do some of the fundamental excercises, stuff like the bouncing ball to show you have a feeling for timing and mass. Maybe do a morph animation a walkcycle and try your hand at a lipsynch?
Again, I find it difficult to say, because I feel these are the sort of things a school should be teaching you, especially if it's their animation department.
