My understanding is that the USPIS pre-employment polygraph is very similar to Phase II of the Department of Defense Polygraph Institute's Law Enforcement Pre-Employment Test:

http://antipolygraph.org/documents/dodpi-lepet.pdf

The above document is used as a guide for training polygraphers to administer the procedure and includes all the questions asked. It will be easier to understand if you read Chapter 3 of The Lie Behind the Lie Detector first:

http://antipolygraph.org/lie-behind-the-lie-detector.pdf

I do not know for sure whether Phase I questions (counterintelligence) are also asked, no do I know what the failure rate is.

There has indeed been very little discussion of the USPIS polygraph program on this message board. To find the few message threads where it has been mentioned, be sure to set the scope of your search to cover more than the past 7 days (which is the default).