Autodesk Vault Customization

[#1]

In the "Hello World" SDK Vault extension, can the property grid that appears under the "Selection Info" tab be edited, so that it contains more file properties?

[#2]

Yes, you can edit that tab.  Displaying file properties means using the web services to communicate with the server.  If you want an example, I suggest Vault Web View, which reads the URL property and loads that web page in a tab.