The whisper repeating is interesting, it sounds to me similar to a child on the show "The Middle" that we have seen a few times. The youngest boy, "Brick" is most likely highly gifted but he seems to be autistic/asperger's possibly. Maybe you can check that out and see if it is the same thing.
Regardless, DD used to do things similar to that, especially the lip licking. She would have the dry lips/rash all the time as well! She hasn't done that in maybe 5 years now, though. I think she just slowly figured out how to not do that, and it eventually went away. I think at 6, behaviors like that are somewhat normal, if they do eventually go away.
This might be an already answered question, but I'm assuming any type of autism spectrum disorder is not present? If that were there, that would make a lot of since, but I imagine you wouldn't be asking unless you were fairly sure that he didn't have anything.
