I'm not sure if you have proof that she has accessed other kids records, or if you're assuming that she did. Ususally kids are quite aware of who has the best and worst grades in their class, so it may not have been what you think. If you're sure that she is sharing confidential information about other students you should report it to the school.
Is she actually giving your daughter growth hormones? That is a perscription, and a doctor would have to prescribe it to your daughter. A pharmicist can't just give it out freely.
What is it that you want to happen with your child's step-mother?