I'd recommend The Professional Handbook of the Donkey by Elisabeth Svendson. She founded the Donkey Sanctuary in Devon, England, and has travelled all over the world, championing the cause of donkeys in distress.
They also have the Slade Centre there; providing donkey riding for children with special needs. It is a marvellous spot, with wonderful people.

I don't know much about gaited donkeys. I can tell you that donkeys can be very smooth; they seem to move their back less than a horse.

Your stables may see the donkey as more of a mascot, but honestly, they are worth it. I don't find donkeys stubborn at all; simply highly intelligent with a much better grasp of physics than horses. They are able to say, "I outweigh you, and can be resistant to your strength pitted against mine. However, if you would like to negotiate, I can be convinced."