I don't mean to downplay your little girl A. but I couldn't help but laugh when I read your story. It sounded exactly like my children, only I have two girls, not twins, one is going to be 3 and the other going to be 7.
I always felt the need to discipline them both when they were HORRIBLE but then my mother said something once to me that kind of stuck, Their behavior is part of their character, the more you change that, the more you change them. This is not to say you don't discipline them, just be careful how you do.
I stopped going out with them, especially to restaurants. You would think my almost seven year old would know how to act but sometimes its just the opposite! She gets my three year old to do things that are very dangerous for her to do!
Don't worry about your little girl being a cute polite little girl, she isn't going to be. Enjoy her for her flamboyance, her loudness, her screams, for one day, she may conquer the world. Of course you may not live to see it, just kidding.
My three year old does some of the things you describe of your five year old. But she is also like your son, she is well aware of her behavior and is very smart about it. She knows how to manipulate the situation already, can you believe that? Appreciate him for who he is, but don't expect your daughter to be anything like him. I had to give up the dream as well.
My kids are exact opposites and they hardly ever get along. And sometimes I sit back and pray about their future (and mine), because I see the calls to the office coming, the fights they will have over nothing, as teens, etc.
My sister has always told me, take care of them now, so you don't have to when they are older, it will be much harder, if at all possible then.
I hope this helps, I just felt compelled to respond to you.