Okay, here's some basic info- again, feel free to ask questions and I'll do my best to answer:
The governing system is the royal family, the regents, and basically the military below them. The royal family is Krysta and her parents, but they have lots of cousins and second cousins and stuff, so it's not a big deal that she'd currently the only heir.
Pixie can look however you like- Krysta has silver hair because she's royal, that's the mark of the ruling bloodline, but that's about it.
They'd live as long as the forest lives, but they can choose to "fade" when they're older if they get tired and just sorta wanna rest. This means they basically just become less and less corporeal until they actually become one with the magic of the forest. They age the way humans do until they're like 20/25, then aging slows down drastically.
Average hieght if between 7 and 8 inches. Krysta is short.