Yeah, like every modern fantasy, Star Wars is really influentiated by the various mythologies and real life occurencies. Don't get me wrong, Anakin story is no doubt a tragic one, however I feel that Achilles is, in the end, even with all his weaknesses, a more noble character than Anakin, because, as you said, he was not corrupted, only proudful.
That parallel between C-3PO and R2 and the greek chorus is interesting, I never thought about it. I always saw them more as comic relief. I reckon it's pretty hard to imagine the greek chorus as a comic relief tool.