[Snowflakian]

The thing to remember with cap, is 2 fold.

1.) This is a period piece set in the 40s.
2.) It's NOT the comic book captain america.

Remembering these two things will help on many ends.
Mostly because of the USO angle of the movie at first, and then the change up to in the war. So he's going to have roughly 3 costumes.
1. USO show costume.
2. His own combat suit for going out on his own.
3. A new suit when they decide to let him fight in the war formally. (which originally was the USO suit and combat suit meshed together. No clue how much of that has changed.)

It may even get special revisions based on the situation. You know going into Normandy without a helmet, or dropping out of a plane without a helmet may not be the smartest thing anyway. But why keep it on if it obstructs your view of battle once in close quarters or city fights?
None of these will really dictate what to expect in avengers though, as all the suits will be dated on purpose for this being a period film. Shield will probably give him a new costume for the avengers.

Chris Evans looks fine like he'll pull it off perfectly. Just don't go in expecting verbatum comic accuracy, or even modern comic accuracy. This is a take of trying to do it in the real world with how governments think and work with tax dollars. You have to consider the troop rallying potential of the time as well, and uniqueness of his situation.

Ironman skates, because the entire premise is an arrogant genius who decided to strap rockets to his legs more or less. Suspension of disbelief? Definitely, but that goes with the entire ideal behind Tony Stark being a genius. Nothing is impossible, it just hasn't been made yet.