#1: Nice. I like the angle of the photo, but it just screams "slow shutter!" to me. ISO 400 is probably too slow. maybe you could bump it up to 800 and (if that's not enough to freeze the action) maybe even underexpose a bit. With a faster shutter and a lower POV, I think this photo would be a winner.
#2: similar problems to the ones in #1.
#3: It's like the friendly twin of #1. Lower POV and faster shutter speed. i would still raise the shutter speed and lower the angle a little.
#4:Meh.. I don't know. Angle looks boring to me. And the shutter...
#5: I'd have moved to the left side. I think this shot would REALLY benefit form seeing the guy's face. Oh, and a lower POV...