That poor hen with the twisted toes - it's too bad you didn't have her when she was a little chick, sometimes taping their toes to a cardboard cut to fit, will straighten them out. The chickens really struck it rich when you took them in. They probably are picking on the little hen because of her size. They accept the bantam roos because they are male. Don't under estimate them - lots of people have spunky bantam roos that sire a lot of progeny.
If you were so inclined you could make the little girl a house chicken or at let her come in at night so the others would leave her be.
I'm sure she sleeps on the horse's back so the other hens will leave her alone. It's good to have a friend.
PS I enjoyed your story so very much. I hope you will continue it in "Stories and pictures of my chickens," thread - so others will see it.