Yes, the Han-Tool will tell you if you need to use a Hansen Easy Fit Poly or Compression fitting.
Yes this is normal, but when measuring the outside diameter of the pipe (inserting the pipe into the tool) if the pipe sits accurately on a compression fitting mark then that is the correct fitting. Remember the difference is inside diameter pipe (ID) and outside diameter pipe (OD) so one pipe the ID has to be a correct measurement and the other the OD has to be a correct measurement.
Yes, hose is generally an ID pipe.
No under normal wear and tear conditions the Han-Tool markings will last as they are laser etched onto the tool
No we can only guarantee the accuracy of our own fittings