Custom domain name for hosted site

I'm in the process registering a new domain name for my askbot.com hosted site (:

What do I need to do to get my new domain name to point to my site?
Can I get the expats.askbot.com subdomain to redirect to my new domain?
Is there anything else that I need to do (e.g., update the site entry in Django admin)?

We will change the domain name for you, no problems, but there will be issue with some login methods as they are tied to your domain name.

There may be a technical solution, but you might also tell your users to recover their accounts via email or ask creating a password before you change the domain name.

We will have to make the change on our end, there is no user-facing UI for the domain name change at the moment.