Seeing as the 10 Rings is a multinational terrorist organization, I don't think we have to worry about him being a "yellow peril" villain. He'll be a terrorist. As for him being Asian, well, that's a given. He'll probably say he's a direct descendant of Genghis Khan and that the title of "The Mandarin" was first created by Khan.
As for the ring themselves. . .my guess is they are just highly advanced technology. Perhaps mini-ARC reactors each meant to power a different function. I doubt they'll go the alien route.
As for other villains. . .Crimson Dynamo could work like he did in the Ultimate Universe. Instead of a single threat (As you said, it'd be kind of redundant with Iron Monger already used), he controls an army of Crimson Dynamos.
Or they could use Fin Fang Foom.
EDIT:
http://www.cinemablend.com/new/Scoop-Iron-Man-2-Plot-And-Villain-Details-8736.html
Or, they could use The Mandarin AND Fin Fang Foom. But, Thor needs to stay a cameo. He's getting his own movie and will team up with Tony in The Avengers. He doesn't need anything besides a cameo in Iron Man 2. I like the possibility of Fury playing a bigger role, though. More Sam Jackson is a good thing.
