If you go full time at the post office you will then have insurance right? Just from reading your post you seem happier at the post office, just my oppinion but that's what I got from your post
Will you be able to get full time hours at the post office? In so far as the school job another pro to that though is that when your child is school age then you are at the school and I think get a little bit more of what you want for her, such as certain teachers etc. Is the school in your town where she'd be attending? As far as gossip. Huh I think that goes on everywhere and at every work place.
Best of luck to you.
Elaine