...or she was a brainwashed child assassin? Think 'Hanna' meets the 'Manchurian Candidate' with a dash of 'Leon' and some River Tam.
On the other hand, I've seen interviews with SMJ in which he says he thinks of his Nick Fury as the same one that fought in WWII and there's some mechanism--as yet unexplained--keeping him young. Assuming he's right, there may indeed be something else out there. (Note I have not yet seen TWS yet so I don't know yet how he's been kept alive all these years...though I can probably guess.)
Actually wasn't it Black Widow who told Cap that (besides Banner) a lot of people tried to replicate the super soldier serum? It'd make sense that the Soviets would be just as eager to get their hands on it as any super-power.
As for her accent...um, she's a master spy and expert infiltrator. She can have whatever accent she wants.