I own 3. Mom is 32 and is missing most of her teeth. Her days are numbered unfortunately. Her boys are 20 and 21. I had a miniature that lived to 36.
Donkeys are sensitive to correction, so harsh training won't work. I broke one to ride years ago. They are definitely different than horses. I think they are more like dogs in their manners.
I see he's with goats. Hopefully he's nice to them. Mine will go after my goats if they get into their pasture. One of my goats is slightly paralyzed on one side from his encounter with my donkeys. Mine have killed ducks in the past, and are dangerous to dogs. Mine are good predator deterrents. I've even seen them chasing stray cats out of the field.