Domain Mapping and email addresses

I have a VPS for all of my websites, and really, I know just enough about how to run it to get by (in other words–I know just enough to be truly dangerous!). I’ve had separate installations of WordPress on each website until recently when I’ve been converting them over to a multi site installation on my main website. I have some questions about Domain Mapping and how it works in this case.

1) Website 1 is where WPMS is installed and I now have a dedicated IP for this site. Website 2 is on the same server (but not the same IP) as Website 1, and is still up and running independently. I’m currently importing databases from Website 2 into a network site on Website 1, but once everything is working properly, do I need to assign the A record for Website 2 to the dedicated IP address for Website 1 at the domain registrar or do I do that in WHM on my VPS?

2) What happens to the hosting account in WHM for Website 2 once the dns is resolving to the dedicated IP on Website 1? Do I just delete the files and terminate the account in WHM?

2) For some of my websites that will be migrated to the WPMS on the dedicated IP, I have email addresses like “me@website2.com”. Is it possible to still have these email addresses once Website2 is running in WPMS? If so, where do I manage those email addresses?

Thanks in advance for any advice or help!