[Exchange server DNS and Calender questions]

First off, some info. I'm administering a Windows SBS 2003 box, which is the DC, DNS, and Exchange server. It's a very small office <10 users.

Question 1.) I know that all my clients need to use the DC as DNS, but what about the server itself, should it be using itself as Primary DNS, or my ISP's IPs? I took over this job from another person who built the server in the first place, and I see all sorts of DNS errors in the Event Viewer, going way back. "The DNS server encountered a packet addressed to itself on IP address 192.168.1.2... "

Question 2) I have 2 clients in this office that use the Exchange server to share calendars, but that's it. The Exchange server is not now, nor has it ever been used as an email server of any kind. If I was to migrate this to another server, would I even need to migrate anything? Or could I just set up Exchange, and their calendars will be 'imported' from their respective Outlook clients when they connect to the server?

Thank you in advance for any help!

--Phlod