I agree with all of your points, (except that I can't confirm or deny #2, as I only paid attention to the 40's style rings).
I would add, #7: All original 40's style rings have a sloped/angled skull when viewed from the top or bottom, (ring laying down flat on the table, and you are looking straight down on it).
#8: There were three different engravers that engraved the originals, each having a slightly unique and distinguishable appearance, (sometimes in size), while each engraver still used similar styles of blade strokes to make each of the similar letters and numbers.
#9: Heinrich Himmler is rolling in his grave, due to the fact that all of us are making such a big deal out of collecting his beloved TK rings.
