1. Yes; although I have seen variants that more closely resemble the so called falming bomb. This is undoubtedly due to the variations in the diemaker's cutting of the face of the stamp and through wear on the stamp face.
2. Note Sam refers to the proof as being on "Spare parts"; I have never heard of the US Army proofing spare parts and I was a part of that group for 22 years. Likewise, as a Luger collector for now 40 years (Damn, I must be getting old!) I have never seen or heard of any such markings. I have no idea where the information used as the basis of this entry in WOL came from. My hunch, and it purely a hunch, is that there may have been some artistic liberties taken in converting the photographs into artist's renderings, but whadda I know about art?
3. The Taurus proof
4. Your guess is as good as mine.
I think it is salient to note that there are mistakes and screw ups in virtually every book on Lugers. Some are more readily apparent than others. Some are also hotly debated by the collecting fraternity. In the final analysis, one must follow what his intellect tells him is the most logical and rational explanation. The wonderful thing about toggle-tops is that there are so many little weird things that pop up across the 300 plus recognized variations that one simply doesn't get bored.
Tom A. <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />