Accuracy and Reliability of Hawk-eye & Hot Spot

The fact that the "Decision Review System" is not being used in the current Test series between India and Australia has given rise to more BCCI bashing.  
Unfortunately, no one seems to look beyond BCCI's reluctance and delve deep to discover why there are no uniform answers to the following questions: 
  • How reliable is the Hawk –eye and the Hot spot?
  • How do they account for the variable bounce and the movement off the pitch?
  • How accurate is the technology in predicting if there is a small distance between pitching and impact point?
  • How does longer distance impair the accuracy of the prediction?
  • If the technology is accurate and reliable, why are there instances when many viewers disagree with it?
Actually, the developers of the technologies should assuage these concerns. However, they too appear reluctant to come out with a yes or a no answer without adding riders.