Adds something like a pot belly stove that burns firewood as fuel. {snip}
Except from torches (big and wall mounted, etc.), fireplaces and furnace should, indeed, require wood to have fire. This would create ambiance in the game. For example, you are approaching a house in the middle of the forest and all is pitch black... with eventually murderous creatures or other dangers... you go in and use some wood to light up the fireplace and finally have some light (why not warmth as well? The cold could cause some side effects, like slowing you down...). Or, another example, you're again in the middle of the forest at night and you see lights inside a cabin... ...
You could even extinguish the fire and light it up again later on, and other players could potentially steal your firewood from the fireplace
Bottom line, great suggestion!