IIS and domains

Hi,

I am preparing to run a little webserver on the internet, and are having some concerns.
I have installed IIS on my Windows 2K Professional.

Now. Lets say that I own the domain msn.com.
Firstly. How do I make IIS see which domain the person enters, so that it can open the correct folder on the server?
Like I have the folder wwwroot, where I have two other servers, one for each domain (msn.com as msn and microsoft.com as ms).
Where do I specify which domain goes to which folder?

And another thing. I will be running my server from an ADSL (512/512) connection, which has 1 IP.
How do I take my mail, and make them into any POP3 account? Will the built in mail function work right away, or do I need more?
The reason why I am asking, is that I already have my website up on hosting, and would like to know if I could expect my mail to work right away, or if it would be a problem to retrieve them.

Thanks for the help!
~Casper