Q. How does SharePoint retrieve ASP.NET pages from the content databases?
A. ASP.NET 2.0 introduced a new pluggable component type known as a virtual path provider. The idea behind a virtual path provider is that it abstracts the details of where page files are stored away from the ASP.NET runtime. SharePoint retrieves ASP.NET pages from the content databases using this concept through the SPVirtualPathProvider class.
Q. Can we have a SharePoint Farm for just a service application?
A. Yes. You can now have an entire farm that can scale out, whose job is only to provide services to other farms.