I guess it's not a spoiler if you don't know what's going on, right?

There is a story in works, yes, an actual story, not another RP I promised to rewrite one day. it's F:E-related, thought as loosely as possible and it has AU versions of Amber Drop and Rain Dancer and this is something that happens in the story at some point.

Yes, her scars are explained there and so are her hooves (and tail).