The more modern designs have “rebreathers” built into them.
They re-introduce air into the upper section of the firebox to burn off the unburnt gases, making them more efficient. Realistically, you want to see no smoke coming out the the chimney. No smoke means a complete and total burn of all the gases. Now, that is assuming seasoned wood, proper chimney draw, etc.
I have two.
One is a furnace providing heat via HVAC. BUT! We have had when the power went out, keeping it going prevented the pipes from freezing, and the first floor warm.
The second is a stand alone wood stove, no HVAC. It is small, and hindsight I wish we would of gotten a larger one. It has a realistic burn time of about 5 hours. Had we got the next size up, the burn time would of been closer to 8 hours or stock it at 10pm and not have to worry about it till the next morning.
Additionally, I would look into purpose built wood stoves to cook on. We had a old cast iron stove that was great, except it had a very small fire box. But once it was hot, I could make pasta on it easily.
In short, I would recommend to go one bigger than what you think you need.