S.R.
Dear I.,
I haven't had your particular experience, but I did notice some behaviors in a friend's child which were equally obnoxious two years ago. Now she seems to have outgrown a lot of the negative attention-getting behaviors and tantruming. I know her parents spend a lot of time talking to her to help her understand her needs and positive ways of getting them met.
So, for instance, why are you crying/yelling, ...? What is it you want? Then something like, "do you think this is the best way to get that?" Or, "what could we do to help you?" What they are really good at as a couple is responding to the daughter's hype without showing fear or anxiety. They just seemed to accept it all as normal. At the time I thought her incredibly spoiled and willful, but after a recent visit, I have to say she has matured and developed fine manners as well as evidencing the ability to consider the needs of others in a thoughtful, caring way.
So, while taking in the many suggestions you receive, don't forget that she is only 7-years old and we have a very perfectionist society. Allow her to explore. Encourage, support, teach and mirror her behaviors so that she can learn better ways to deal with life and frustration. It might help also to get an older cousin involved, a youth she likes and trusts who can help her understand that such behaviors don't go over big with her peers (or anyone else). Kids learn a lot from other kids. Being around kids and wanting to make friends is a big incentive for changing negative habits, too.
Good luck and God Bless,
S.