In answer to your questions:
1. Users are notified when it expires.
2. Yes the customer is emailed when the listing has expired
3. A basic notification that the listing has expired, with a link to the customer dashboard so they can choose to renew the listing if they wish.
4. No, there is nothing in the admin dashboard settings to change the email so you need to change theme files.
5. No
6. You would need some coding knowledge to make such changes.
7. Thanks for pointing this out, usually we do show all color options on the demo site. I will report this to be fixed asap. Thanks.