We have some ideas on how to enable editing a character’s appearance in-game, but it’s pretty far down on our list with so much other important things to do first, I’m afraid.
The game currently does not support modding. We’d really like to support it eventually, but our resources are limited and our priority is to create the best possible core game first. It could be a while until modding becomes possible, if at all, and we can’t make any promises at this time.