Bill, to maybe help with your NMF question, From what I've read, As was with the most of the war (but more so towards the bitter end) the aircraft were never built nor assyembled at one point exclusively, and as the war turned against the Reich, a "Cottage Industry" mentality was relied on even moreso then ever in the past. Many of the components were mfg and shipped to an assy point by numerous points in germany. There are instances where Folks would assy instrument panels and related wireing in sheds and garages out side their homes.
Many of the underside NMF panels and wing sections were sent from their assy points in that way, because they just flat had no paint to put on them, and the upper surfaces were more important to be painted to try to conceal from the now marauding P-47s and P-51s, that had free orders to attack anything they felt was a target. In a nutshell I think thats why you see more NMF undersides. Not that it was desired, just a consaquence of the circumstance.
Doug