Watch This. Unfortunately, @SpaceInvaderOne didn't include the dancing girls that I asked for, but he does do a good job of explaining a concept that's so simple that its hard to explain. Additionally, you can look here: https://forums.unraid.net/topic/57181-real-docker-faq/?tab=comments#comment-564306
In "english", the only difference between using /mnt/user and /mnt is that when the former will only allow Krusader to operate on shares (which is the safer method) The latter allows Krusader to operate on shares and the raw disks, which depending upon what you are try to do has the potential to corrupt data
*Generally*, you never need to touch the appdata path. Ever. Its automatically filled out according to your default appdata path that's set in Settings - Docker.
Not quite sure what you mean by this