AFAIK:
- The API is unified with other drools projects (expert, fusion, etc) and can be found here: http://downloads.jboss.com/drools/docs/5.1.1.34858.FINAL/apidocs/index.html
- You get additional tables when you enable the history log: http://docs.jboss.org/jbpm/v5.0/userguide/ch08.html#d0e2605