In vista you need to open control pannel and find (programs / windows feature) Then you turn on the IIS feature.
If you install community server be sure to get the latest version.
Your last question on .NET 2.0 apps running on IIS 7 and vista. They do, I would just recommend testing before you port those applications over. The items I have seen cause trouble are older .asp applications and .NET apps that use custom 3rd party controls or resources.