You can view details on how I calculate each position by clicking on the position's 'check' or 'x' image. Doing so will open a modal dialog provide that displays detailed information in both a graph and table view.
Getting additional position data is one of my top priorities in the next week or so. The first additional subset of data I plan on using is the Political Courage Tests from Project Votesmart (http://www.votesmart.org/npat_about.php). With this data, I should be able to provide positional information on 40-50% of all Congressional candidates, including Independents.
Finding this same data for regional candidates will be tougher. I am thinking of providing some alternate information for these candidates, such as a Twitter feed or RSS feed.
Also thanks for reporting the error. I will look into it today.