To my knowledge, there are no iron sites in MOH:AA. As for the latter part, there are three ways in which to 'bind' the crouch button. The first being the options menu- very simple and quick. If you like, though, you can edit your config from outside, or use a simple console command. Go with the options menu, for it is much easier.
And if I'm hearing you correctly, you are asking for the bind which enables you to look down the barrel of your weapon? Well, that's not possible in this game. If you're really interested in the iron sites features, I know there are a few good modifications for other games that has that as a feature. http://www.truecombat.comhttp://www.planetquake.com/ddayhttp://www.operationflashpoint.com
The last site is not mod, but rather an actual game. It's available for trial on their site. The first one is a mod for Quake, and the last is WW2 mod for Quake2.
iron sight is when ur weapon aligns into the center of ur screen. Yeah it would have been great to have it, it was suppose to happen when u prone, but they took that out <: P
They shouldnt have put that picture of it in omaha on the advertisement...........