Fitness at Home

I really would love to look like the girls in the video (below) (who wouldn't?). I am about 5'2", and I might grow a little bit more. I am about 100 to 105 pounds, and I tend to overeat sometimes. I tend to carry my weight in my middle/butt area.

I am 15 years old, and I take 3 ballet classes a week (plus Contemperary, Jazz, and Theater), and a pre-pointe class. I am taking the PREP-pointe class this summer, meaning that I will be on pointe next year.
What should I do to build up more strength for pointework? How can I have more balance? My dance teachers say that good abs/core is essential for good balance.
What should I eat for breakfast, and a snack? I usually tend to overeat then. I usually bring money to buy a snack at lunch. Can I still buy something, just not ice cream or hot chocolate -- something like Baked Lays or something?

And what are some foods that will keep me full, and boost my metabolism?

http://www.youtube.com/watch?v=wpnL6MC8f...