I do not know for sure if it's his parents, but the seller says it is. Personally, I would never use a dog without a pedigree for breeding, so no, he shall not be used for breeding. The seller can't have him anymore, because she must move to a place where it's not allowed to have a dog.
I'm not sure I know what it mean, that his tail is not docked?
Those of you who have a very dark Yorkie, can you possibly put a picture in here that I can compare with?