That mare will be pretty when she's in shape for sure. As for the donkey -- how odd. I wonder if that's just a sway back or something else. Let us know what the vet says.
Donkeys are very loyal animals. You need to develop a relationship and consistency with them. With you going away for a month that wouldn't happen even with a donkey without her sad history. If you let donkeys tag along with you everywhere you go, but just kind of ignore them -- on a long leash basically -- as soon as they start to get comfortable with their new environment they will get curious about you. They have to see a person as their secure and constant place in order to really be friendly. If you can manage that, she'll follow you everywhere, even when you don't want her to.
Good luck with the poor lady..