Hi Ray,
Depends, the boot monitors might be hooked up to the house mixer as well, in which case you just use it’s volume control for that.
Can’t tell you what percentage. Use your ears! Personally I set my monitors to a level that I can hear them slightly louder than the house PA. And I turn them down as soon as I am done. More work, but better for the ears.
Keeping the EQs at 12 and the fader at 0dB is always a good plan on the mixer. Adjust your gain so that you have 0dB on your controller channel, 0dB on the master out controller, 0dB on the channel input on the A&H. Now you can turn down master on the controller in the knowledge that you can turn it up to max 0dB level and be in the green. The house engineer will love you for it.
.
