If you are putting it in your upstairs living area, the blowers are normally on the bottom of the back of the stove, so the air circulates pretty good back to the stove. No return air duct work is normally needed unless you are hooking into your duct work like in a basement or something.
On my hyfire, I connected my return air pipes directly to the inlet blowers....Hyfire II - Return Air
As for sound like they said, the combustion blower runs 24/7, the stoker, on/off every so many minutes, and the hot air blower will either be on/off or vary in speed depending on your model. The stokers do not run/heat without electricity.