Do lots of cardio, I guess, and wear dark colored pants/skirts.
If you've always had a big butt, you'll probably always have it. Just don't let it get fat, or that will look really bad.
Love yourself, girl! I totally understand what you mean - same problem here.
Speed, speed, speed! It's one thing you can't have too much of in a fight.
Learn to grapple - I believe kickboxing has little or no floor techniques, and this will be important.