I agree that you can remember things that happened before you were 6, and I also agree that what the adult did was sexual abuse. The stuff with kids your own age would not be considered abuse; curiosity about other children's "parts" is normal as is wanting to see/undressing. However, if that second memory bothers you, it is something that you might want to address in therapy, journaling, prayer, symbolic things or however you choose to deal with icky stuff from your past.