The only way to safely change you race, class ect is to start a new game. However I think the command you're looking for is "reviewstatsmenu"
Welcome to Gamebanshee. I'm Ml, I've been modding Morrowind for nearly two years now so if you need any help post a thread or PM me. You may be interested in my sticky at the top of the forum. It might give you further help with your problem.
Here's a template for the birthsign. Just mark some white dots on it then join them like dot to dot.
EDIT: Sorry I forgot the link.
Blank Birthsign - Planet Elder Scrolls