A lot of girls won't wear anything or just thongs while wearing skirts. I have one girlfriend that never wears panties and always wears mini skirts unless she is on her period.
When we go out for a meal sometimes, my friend Niccole often wears just tights under her tight black mini skirt with no panties. This is usually to avoid her pantie lines being visible.
Some definitely do, but my guess is they are in the minority.
No,they wear skirts with panties.
Some girls do if they are trying to show their butt cheeks in public:)
Depends on the woman.