Faldage, you're qutie right that the homomonym J.A.P. and Jap are separate terms, and that each is racial epithet slur. (The former perhaps cannot strictly be called "racial", as it is limited to a particular subset of the racial group.) And "wop" is also a racial slur.

Some of the other terms mentioned, however, are not racial slurs:
WAVES = Women Accepted for Volunteer Emergency Service.
WAC = Women Army Corp
WRENS = Women's Royal Naval Service.
SPAR = women's reserve of U.S. Coast Guard (contraction of motto semper partus, "always prepared")

BTW, credit here to bartleby, not to any encyclopedic knowledge on my part.