You stopped by to pet a random horse? I wouldn't suggest doing that. I know some owners can be pretty anal when it comes to strangers coming up to their horses. Especially is they're young or hard to handle.
Also have to say try to avoid random horse visits unless you know the horse; you never know what kind of behavioral issues a horse may have, or how the owner may feel about it...better safe than sorry. :)
The riding pictures (since I have time for a quick critique)
Pick your hands up! Also widen them a tiny bit. In the trotting pictures, you almost seem to be perched on your horse. Be sure to sit down on your bum. Other than that I can't see much from the angle
I always have problems with my hands :( I always start off with them in the right position, but as I go along, they always sink back low...
As for the trotting, the first one on the trotting makes me look like I'm perching, but that picture looks really bad.. lol.. normally its not like that :P