I might be mistaken, but isn't "Dead, D-E-D Dead" also a movie quote?
If so, we've seen precious little allusion to it since.
Perhaps he doesn't like talking about the time he ate someone alive?
Apparently if the senior council pooled their knowledge, they would have all the information about Harry's past. Seems like that would kind of undercut this theory before it gets much momentum. If the SC knew that Harry was Kemmler reborn, I think they'd have a more violent reaction.
Heinrich is a given name of Germanic origin and cognate of "Henry".
Harry is a male given name, the Middle English form of Henry.
D-E-D dead is Jim emphasizing dead and being cute at the same time.
I know it was used in Robin Hood: Men in Tights (here's the specific scene), but I don't know that that's the first usage.