Originally Posted by gunslingercbr
I think many of those questions can be answered in the Ultimate Guide to G.I. Joe 1982-1984 book.
Not for a lot of these, the ultimate guide doesn't get into this level of minutia with undocumented variants.
Though some can be answered by the guide. Bellamo states that there is a thick and thin thumbed straight arm grunt as asked in your first question. All of the straight arm figures have a variation like this.