has there been any official response as to a) whether the the currently downloadable reference files are indeed for the final release version, and b), why it is being reported that there are (at least!) two board versions being sold in the first batches of the Due available to the public?
a) No
b) No
You were perhaps expecting feedback from the Arduino team? While they have posted more times in the last couple of weeks than in the entire history of this forum they still pretty much ignore us.
I did see Massimo give a non-explanation on another similar thread I think, something about we haven't got around to uploading the right PCB file or similar. I rather cynically suggested that may to give them a head start on the clone makers, I can think of no other reason to delay a 2-minute job like uploading a file. Mind you I wouldn't blame them if that is the case, they must get sick of people profiting from their hard work at their expense.
Rob