When you trim them, trim that outside wall on the inside toe a little shorter than the inside wall, this should encourage it to roll back over so it is straight. You can only get banamine from the vet, I've never used it for hoof trimming so if you can't get it, it isn't necessary.
Looks like maybe Kiko cross. His hoof doesn't look to awful bad. Don't get me wrong it needs trimmed really bad, but I have a doe that I bought back in the spring that had really bad feet an Im just now starting to get her back up on her toes. He looks like it should be an easy fix.