Are door dings repairable and if so, how?
Call your local Mercedes or Porsche dealer and ask who they use for paintless dent removal. I think I paid $75 last time.
Ditto. If someone really cares about their car, they'll get small stuff like that fixed immediately. If your question was whether the paintless dent repair affects value in a negative way, it's undetectable if done properly. Much better than repainting, which can affect value.
Paintless dent removal doesn't work if the ding is across a crease in the panel, or if they can't get their tools to the inside of the panel. They will often drill a hole in an inconspicuous place in order to get the tool inside a difficult location, then plug the hole with a cap. They can do some marvelous work on many dings, but others they can't help at all.
Had 4 done on my boxer. They were sort of dimple dings, no sharp crease and no damage to the paint. And you can't tell there were ever there. $235.