I have a 10 year old daughter. I don't think she would have processed the cause/effect if I had cancelled a party when she was 6/7 because of bad behavior. Kids don't want stuff, they want our attention and time. I would be more inclined to have the party which is an event you will share, and forego excessive gifts.
I think those "fits" are ways of testing boundaries, but I think if you are going to deprive her of a possession it has to be immediate, kids that young don't have perspective about future events yet.
I also think having an even keel yourself will help her develop a less tempestuous personality. Cancelling the party is pretty major and sort of represents going to extremes. I think contrasted to past events where you have overindulged her it can be confusing. I know constancy is what I missed growing up with an AM. It was the extremes that created trust issues for me.
Don't worry, when my daughter hits 13 I will be here begging for advice!
