Throughout Trek history the answer would be
No
No
and maybe a yes (This was after Roddenberry died)
Here's some of the infamous rumors floating across the web, take it with a pinch of salt
The Roddenbery Klingon was a traditional USSR style warrior, something like a Mongolian. Since he wrote the show when the Cold War was at its height its very possible. Why would the Klingons not be based on or inspired by some guys like this?
Romulans are Chinese, the passion, the poetry, the paranoia, Cold-War style stand offs and isolation
Vulcans are either logical Japanese or like the old Russian commies, no emotion and logical marxists.
Vulcans and the Romulans in the show were depicted as two cultures that evolved from the same root, one the Federation can work with (Japanese) the other was stand off-ish in a Cold War (Chinese)
Ferengi might be considered by some to be the stereotype of Jewish banking money grabbers or Oil Sheiks
Jem Hadar had that whole Aryan nazi Germans thing going on
Later the Klingon changed from a USSR warrior to a Viking and maybe finally to a holy Muslim warrior, the Klingon obesssion with blood letting might have some connection to Ashura rituals and the whole Kahless thing just seems to be a bit like this whole second coming of the last direct descendant of Muhammed
But then again you had that whole Cardassians/Bajorians Jews and Arabs speculation floating around when DS9 was popular. I've also heard the Cardassians compared to Dutch and even French.