We met Mulan at dinner on 3/12/06...but since that's the only time I've been to PSB, I don't know how common that is. (The rest of the cast was Ariel in the lobby, Belle, Aurora, and Jasmine circulating.)
If you do wind up going to the China pavilion (it's right next door to Norway), try to catch the Chinese acrobats. Pretty amazing!
Enjoy!