Let me address some points:
2. Kirk has learned a lot. He now understands that all of his actions have consequences. Remember he stated that he hadn't lost any of his crew, that definitely changes in the film. He also makes the mistake of working with Khan, which led to other difficulties (ie: his death). He now knows what it means to take responsibility.
5. Scotty actually has an integral role. He is the one that snuck onto the Vengence and disrupted its weaponry, and he helped Kirk and Khan actually get on the ship.
Something I agree with you on:
No matter what anyone says, her most memorable scene was stripping. Everything else probably could have been handled by others. If you think about it, Spock could have probably disarmed the torpedo.