I tried messing with save files. Basicly just renaming some of them and i noticed you can take files of a created superstar from one and rename them into another slot of another save.
This seems to only work for appearance so far.
These are for CAW 1. I am unsure as to which files the others are for exactly as i am still trying to sort that out. Have no clue if they can be edited though.
CASSBODY0000
CASSHEAD0000
These seem to effect the Carreer stuff. The appearance isn't changed