Do Khunds predate Klingons?
Well, Earthwar in Adventure #346 is dated June 1966. Star Trek premiered in September 1966, (although it was certainly in production at that time) and the first Klingons appeared in Errand of Mercy in March 1967.
Gene Roddenberry always insisted that the Klingons were based on stereotypes predominating about the Soviet Union at the time: ruthless, vicious, heartless, godless, uncultured, vulgar, primitive, ultra-violent conquerers, who would not hesitate to detonate nuclear devices all over the U.S. if they thought they could get away with it.
So maybe the same sorts of ideas inspired Levitz.
(The Romulans mirrored attitudes about Red China: intelligent, mostly honorable, but sometimes treacherous.)
As far as Khunds being one-dimensional characters, remember they were invented by a 14-year-old.
As time went on, they were somewhat fleshed out.
Khundish Legionnaires"Khundia itself is perpetually eclipsed by its own moon, making it a dark and dreary world. Choking on its own overly dense population, the world has become totally overrun by a mentality of total militarism and violence. Even a person jostled in the streets will settle the ensuing argument in the so called court of combat, a form of trial by combat, which is often fatal." (ComicVine)
Most Khunds I have seen are either Yellow, Pale Yellow, Pink (Magenta), or Peach. I have heard of 'Red' ones, but never seen one.
The Khunds in Justice League Unlimited are gray.
On the Supergirl TV show, their name is pronounced
K'Hund.