Email and Mailman with subdomains

Hi,

I have domains where I manage DNS outside of inMotion. I want to point some domains/subdomains to be serviced by my VPS at inMotion.

A couple of questions:

1. How can I configure Exim to accept mail for domains/subdomains outside of inMotion?

2. How can I configure Mailman to have a different DEFAULT_URL_HOST and also for mailing lists to accept mail for a subdomain outside of inMotion?

3. I know Mailman works by setting up aliases for posting, owner, admin, etc... where can I view the aliases in cPanel or WHM?