An outdoor forced air wood furnace hooks up essentially the same way as a
boiler, utilizing the same existing ductwork in your home, usually.
The difference lies in HOW that heat is transferred. A boiler (as the name
implies) uses water to carry the heat to inside the home and uses a heat
exchanger (much like a heater core in a car; a small radiator).
A forced air wood furnace transfer heat from the firebox into a body of air that surrounds the firebox. It is blown into your home with a huge 3 speed blower, much bigger than is found in the typical home. This furnace is typically 20% more efficient than a boiler because heat doesn't have to be transferred to water and then transferred again back to air.
Your home does not need existing furnace and ductwork to work. In fact, the Army Corp of Engineers used one of these forced air furnaces to heat a huge warehouse that did not have any ductwork. They used our huge dual fan ThermoWind 4000 and placed the waterless wood furnace in the center of the building, length wise. They simply ran two ducts into the building at the center and ran one duct to each end of the building to supply the hot air. Then they ran two more ducts to pull the return air back into the furnace to reheat it. This way, they got good air flow through the building.
In a typical home, you would run a supply duct (hot air) to the opposite corner of the home and then put a return duct closest to the furnace to draw the air through the home, giving good air circulation without a lot of vents or extra ductwork. If you find out that one of the rooms like a bathroom is not getting hot enough, you can simply do a smaller run (6") off of the big duct (12") and put a vent in the floor. You can do this for any other room that needs extra heat; probably not the kitchen!
I know that I don't like a hot bedroom so I probably wouldn't run heat into there unless it was on the outside corner of your home where no sun gets to it. You would probably want heat in your foyer and family room, dining room etc. This is something you can do as you go; adding individual ducts and vents as needed.
We have heat exchangers in a multitude of different sizes to fit virtually any size of ductwork. We have heat exchanger from 10" up to 30" and we will special build exactly what you need in any custom size. This typically does not cost much more than an off the shelf part because we have a manufacturer in Texas that basically does everything custom but keeps many of the most popular sizes on the shelf.