Instead of relying on the school or public librarians to inform on your child, why not just ask the child what he is reading? That can be an interesting (or boring, depending on tastes) dinner table conversation.
A child checking out a book on her on volition is not the same as the school taking her for a medical procedure. Everyone but you seems to understand that.
No, not just informing them about an abortion, but actually taking the girls to get one, presumably with the girls' consent.
If a girl got one on her own, then told the nurse or school counselor about it - should the school break confidence and inform on the child? I think the answer is complex depending on the age of the girls (e.g. with a ten year old it is a police/child safety matter but with a seventeen year old, it may or may not be).