Mine is a mikuni. Sits fore and aft on the shelf in the cockpit locker. Mine is on a permanent live - I understand that this always allows the unit to do a full shutdown (run the fan for a bit after the burner is off to dissipate heat etc) which might not happen if someone switches it off at the panel.
The trunking takes a complex route to give vents in the heads, both cabins and the saloon, but it looks a professions install. I retro-fitted the eber trunk insulation. Makes a huge difference, saving both fuel and volts by getting the saloon up to temp quicker allowing the unit to drop to low power setting more quickly.
Air is taken from the cockpit locker itself, so is dry, and will come through ultimately from the vent under the helmsmans seat.
I'll take photos and send them on next time I'm down there.