SciFi/Fantasy: Elves on a mission to find the Elf queens replacement

[Jenn]

A group of people on a mission from the Elf queen, to find and bring a young girl The winter lasts 100 years, they find the girl, she takes on all the memories of the elf queen and becomes the new queen and spring starts.
You can only braid your hair if you kill someone, and for every person you kill you get a new braid in your hair. The adversary is like a dark elf queen and she has some sort of flying kingdom on hot air balloons.

Adult Fantasy, I read it between 2006-2014

[Kris]

Jenn, is this book for teens or adults?

Around what year did you read this book? A range of years is fine.