If you want to use the Audyssey calibrated settings, you can either use Reference or Flat. You can try out both and see which one you like better. Off turns off Audyssey calibrated settings.
I once again advice you to turn Dynamic EQ on.
You have asked somewhere if Full Range will hurt your speakers. It will not. Full Range is what happens when you play your speakers via a stereo amp. Will your speakers be able to play full range is a different question. If your speakers are not able to play full range, they will distort at higher volumes. This is where speaker crossover come to the picture in AVRs.
If your speaker is not able to play full range, ie, frequencies from 20Hz to 20 Khz, then you can imagine what happens if you try to send the .1 frequencies in the range of 3Hz to 120 Hz in movies to your speakers.