1. Tips on transitioning to natural - go to the transitioners forum. There are plenty of advice and tips there that would just be repeated here. It really depends on how you want to transition and for how long. I transitioned by carefully blending my straight hair into the curly hair by doing twist outs, braid outs, and setting the straight hair on perm rods. Oh, and I made sure to deep condition often and trim regularly. Didn't use heat the whole transition. Some people have had success using wigs, weaves, or braids. And some just chopped early. It really depends on your hair goals. But definitely visit the transitioners forum. You may get more response there.
2. Honestly, on a little girl, I don't know how you're going to keep her curly hair straight. They like to play too much. My niece has curly hair and the minute it gets slightly humid outside or she starts playing, if her mother has flat ironed her hair it's a poofball. But you may want to try the Mommy's Playroom forum. They may have some tips there. Maybe using heavy butters after flat ironing? I just don't know.
3. Kinky curly and IC Fantasia gel works for getting that wet stretched curl look. But how thick is her hair? If it's pretty thin, she'll get that jheri curl, stringy look.