My Little Pony: Friendship is Magic - And that, little ones, is how you earn a Cutie Mark.

That's male.

Not necessarily. Vinyl probably has listened to and dabbled in performing music her whole life (seeing as her dad is obviously into music too), but this may have been her first time ever seeing big live performance which made her come upon the realization that she also wanted to do the same thing those guys were performing on the stage. It would be like if you watched Futurama and thought "This is so awesome! I want to animate and create cartoons as awesome as that!" And then you got a mark in animating.