Re: Avengers...will it?
The Avengers have had an incredible number of line ups in their over 40 years of existance, including complete East and West Coast teams, so it is hard to say who exactly "is" the Avengers. This ain't the Justice League by a long shot.
The original line-up was Iron Man, Thor, The Incredible Hulk, Giant Man (AKA Ant Man) and the Wasp. The Hulk quit a few issues in, and was replaced by Captain America, who had been frozen solid in a block of ice since the end of WWII and somehow survived in a state of suspended animation. Thor and Iron Man then quit, and they were replaced by ex-Evil Mutants Quicksilver and the Scarlett Witch, and Hawkeye, a kind of poor-man's Green Arrow.
After that, the changes came fast and furious. Something like 60 different characters have been "permanent", "temporary", "probationary" or "honorary" members since the team was founded, so Marvel pretty much has their choice of folks to use in the film. The only near-constant in the group has been Captain America.
Nick Fury and SHIELD are connected to the Avengers the same way they're connected to a lot of Marvel characters - they both fight evil and sometimes need to work together. I haven't followed the comic books in ages, and have only a vague sense of the recent superhero civil war and the whole super powers registration thing, but various characters and groups in the Marvel universe have had quasi-official law enforcement and national security roles for a long time. Captain America, of course, was the product of a secret pre-WWII military experiment and resumed his contacts with the Army (and his security clearance) after he was defrosted by the Avengers. He would have worked with the OSS (precursor of the CIA) behind and lines during WWII, and also personally knew then-sergeant Nick Fury, who later became head of S.H.I.E.L.D. It is only natural the Fury would turn to an old friend when he needed help with a super-powered meance.
Then there's Tony Stark (Iron Man), whose Stark Industries is the largest military contractor in the Marvel universe. He also has a top security clearance, and his companies produce a lot of the high-tech weapons that S.H.I.E.L.D.'s agents use. (Some of them designed by Reed Richards of the Fantastic Four, who not only shares his knowledge with the government, but with other superheroes. Ever wonder how all these guys have costumes that can bend and stretch, turn invisible and burst into flame without being consumed? Richards invented a fabric that can adapt to the wearer's powers.)
I'm a little less skeptical than some about Marvel handling the casting issue. I guess it will depend on who is cast as Thor and Capt. America.
Robert Downey, Jr. is a fine actor, but he isn't exactly box office gold and Iron Man is, in many ways, his comeback film. (The latest of many.) He still has to be considered a casting risk, so I suspect Marvel got him relatively cheap for an Oscar nominee and Golden Globe winner, and that his contract included not only his Hulk cameo and Iron Man 2 but an option for The Avengers at a price that won't bust the budget.
Edward Norton is another good actor, but not a movie star. Besides, the Hulk is such a one-trick pony of a character, I'm not sure they'd use him for much more than a cameo. (The Hulk in the original Avengers was a much more articulate guy, surly, but not mindless.)
But we'll have to see how they decide to play it and what "period" in Avengers history they choose to base the story on.
Regards,
Joe