Hi aslpride,
Thanks for your interest in EE. I’ve just got a few things to add.
1. The EE license allows for a single installation of ExpressionEngine for 1 entity (a person, a company, a non-profit, etc…).
2. A “Site” in the MSM refers to a unique set of preferences within ExpressionEngine that can be applied to a unique domain, a sub-domain, a sub-folder, etc… For example, we use the MSM to run EllisLab.com, CodeIgniter.com, and ExpressionEngine.com off a single EE installation.
3. The MSM is meant to run *related* internet properties. Though you can have unique settings for each Site a few things, like the Membership database, are shared installation wide.
If you haven’t watched the MSM Video that’s a good place to start.
In your domain examples if all those domains are exactly the same “site” meaning, the content and the visual design is the same and all the domains simply point to one spot, than you probably don’t need the MSM at all. It would be a matter of having your web host setup the domains to point to the primary domain on your account.