Re: Leotard question, underwear or no?
The girls wear their undies for class & under costumes, but they cannot wear them for exams.
For ballet most girls wear skirts, now they're old enough they can wear their dance shorts with their bodysuits so even if it is showing you can't see them. The older girls wear bras & depending on the bodysuit you can see the straps.
When I was in dance we couldn't & it was really uncomfortable.