As to "Did Shakespeare write all that?" One of my old profs said that "If Shakespere didn't write them, someone named Shakespere did."

I doubt it was the same with ACD - While he probably wasn't above the use of opium (I don't really know), much of his life is rather well documented as he was not one to shy away from the eye of the "Victorian Paparazzi." His forays into Spiritualism being one example.

As to Holmes and Moriarty being one and the same - I guess there is the possiblity of a "Dr. Jekyll & Mr. Hyde" thing that went on.

What about Dr. Watson and Mrs. Hudson being one and the same?

Pax yall