Similar Artists generally grow over time, as more people start to listen to your tracks. However, artist biographies are taken from All Music - You can find out how to get information on their service right here.
Spotify Artist Relates is terrible! I dont even think there is a department and if there is, it is only 1 person. Don't expect ANY help from them and it wil take 3-6months for a response, if at all. Responses are generic and they will just tell you to follow guidelines on spotify artist section and verification process. It took me 9 months to get a response from 20 inquires. The only help I got was hitting up Spotify on twitter.