I really like this one, IMO but I think its the best in the set, great silhouette.
This one is awesome too, really like the perspective, great depth.
The sketches are awesome, better than a lot of the photos. I don't know if your program is only photo or if its mixed media, if it is then definitely keep those in there.
In terms of your portfolio, you want to show a large range of images, pretty much everything you have now is either a landscape or nature oriented. Most schools are looking for well thought out images, subject matters more than quality/composition, they want to see that your thinking about what your shooting. In that sense, I'd take out the more random photos (flowers, trees, paths, box). Anyone could have taken those, where as something like the silhouette shows more planning and creativity.
Best of luck, I'm also applying to art school and its a headache, but the programs are awesome. I feel so bad for all my friends who are going to be writing 22 page poli-sci papers.