Customizing the remote access site: for the most part, there's no customization available to the end user, as the Remote Access site is an ASP.Net web application. What little Microsoft "supports" is detailed in the Windows Home Server
SDK documentation.
Some users have managed to customize the start page in various ways, changing layouts etc. But that's not supported by Microsoft.
I'm not on the WHS team, I just post a lot. :)