C&C per req:
1. Good effort on the fill flash, but I thin it's a touch hot; the specular highlights on her check are just a bit too bright, and I think the composition would be greatly improved were there more scene in front of her than behind. Consider using a polarizier to help reduce the strong reflection off of the water.
2. Better exposure here, still just a touch hot, but not bad. The image desparately needs to be leveled, and I'm not really fond of the large rock/whatever in the foreground. I think most of that could be cropped with no loss to the image.
3. This one also needs leveling, and I think a crop, to remove the LH half of the image; the compositon with the subject foreground and tower background works well, but there's too much empty space image left IMO.
4. Probably the strongest of the set, decent exposure, again, badly out of level, and with more space behind then in front. When composing, it's generally better to have the empty/negative space on the side that the subject is looking toward; that is, have them looking in to, rather than out of, the image. Also, watch the little details; her necklace is crooked. These small things can have a major impact.
5. This would have been a MUCH better image had you not composed it so that the tower is growing out of her raised knee; it looks rather like a Meccano mushroom! I think this warrants another attempt at the monochrome conversion. It's overly mid-ton ruch and lacking any significant black or white.
Overall, this isn't a bad set, and I'm glad to see that you're using fill light and diffusion, but you need to get that light off of the camera for best results..
Just my $00.02 worth - your mileage may vary.
~John