Well, I had the feeling seeing the pictures that they'll go for the clichê of dysfunctional team and then becoming buddies. Like Cox said, they will understand each other because they're almost renegades and that will connect them.
About Daredevil, Hawkeye is a regular human "with very specific skills", like Black Widow and Falcon, which to me is worthless to the stories and still he's there. Daredevil is a super ninja in the level of Batman and plus, he has enhanced senses. Doesn't make sense what you say because if someone investigates, pay a little attention, or just open the newspaper (that extensively covered the Devil Of Hell's Kitchen) will discover that this guy knocked the **** out of a gang, alone, with no guns. If that it's not worth to keep a tab on a human like this then I don't know what kind of leader Tony is.
Luke is more powerful than even the Captain America.
We will discover about Iron Fist in the next month, but was said that NY will recognize the Defenders, because, let's be honest, to unite those people you'll need a threat that will hardly be unnoticed by the people of NY, and so to Tony Stark that lives in... New York.
Like I said, it's not going to happen, but it's just horse**** what you've been told that it's impossible to introduce the characters for other than fan service.