For the most part I use JPG with hardly any compression so I dont lose much data.. Oh and its every time you save not every time you open you lose data
RAW I have recently started using for night matches because the quality os so poor (only the floodlights to light the scene) and wiht RAW I can manipulate so much more and quicker.
Colours.. I have eceryhting default and a epson r200 printer and everyhting seems to print hunky dorey