Most people prefer a light cycle. Something like 12/on 12/off. However, Dollface has been growing stuff, especially UG, with a MH going 24/7. That's the first I remember somebody giving the finger to the whole universally-accepted on/off principle.
Regardless, you're definitely going to need to be misting, with at least a spray bottle of water, daily or so. You can get creative and fill the bottle with a NPK and/or Micro mixture, but I'm of the opinion that straight water is pretty OK.