Ikno
I’m not addressing everything but I’ll start with the pants. She can’t be allowed to bring other kids down. In most schools such a kid would have been expelled by now. Bottom line is a kid has to obey the school rules and if the school has a dress code for their students in and out of school it must be followed. I think the girl has to be made to understand that the school can’t keep her if she’s ruining other kids. No school tolerates this. You also have an issue where the school is teaching different hashkafah than the home. This can cause lots of issues where the kid can feel confused and frustrated. She hears one thing from you but her parents who I assume she loves and respects have totally different views and possibly tell her that she doesn’t need to believe all the stuff her morahs are telling her. Complicated situation. I would say that a mental health professional should speak to her and try to get to the bottom of her behavior.