RE: Built in reports for Business Analyzer
The reports are all of your SSRS reports. In the Business Analyzer configuration you have to enter the URL for the report server web service URL which should follow the path something like:
http://<servername>/ReportServer
As for the "stock" or out of box reports it uses you can go to the configuration to see which ones are being displayed and then back track through SSRS and open the Report or KPI and view the datasource to see what it's constructed with.
There should be a business analyzer documentation in your Dynamics GP file location on the server under documentation.