Can I change my .mac email address?

I got a .mac account around 10 months ago. I haven't used it much but now with the increase in space I plan to start using it a lot. I'm not happy with the email address I created so before I start giving it out I want to create a new email address. Is it possible to do this? I know since my subscription is almost over I could simply wait and do a new .mac account instead of renewing. Also, I've heard that you can create a email only account under your .mac account and use it and then at the renewal of your primary .mac account make it into your primary account? Is that true and if so how much space do you have while it's a email only account?