Somehow I missed this post, hopefully you'll read mine.
It seems that you are shifting to a pure mass heater, no barrel. Since this can be built as an upright monolith it'd fit inside the 5' x 3.5' footprint. The location in room E would be ideal, the adobe inner wall will get warm as well. Room F and its batchroom will be very comfortable. Room C won't be heated this way, only marginally. With all the doors open all the time, the rest of the house will get warm(er) eventually but not as much as room E and F. Most of the heat from a pure mass is radiation, coming more or less at right angles from every surface. So, not much warm air to distribute through the house.
Pure mass heaters are fed once or twice a day, burn their fuel within an hour or maybe two and go out. Those heaters have a door and all the fuel is fed in one go, or that's the general idea. The fuel can be larger also, it doesn't have to be branches or the like. The masonry of the heater will take up the enormous amount of heat that is generated by that roaring fire and gives it slowly to the room during the following 12 to 24 hours. Most pure mass heaters aren't small, weighing several tonnes. Suffice to say, the room where those are will be warm all day and night. Due to the fierce burning, most mass heaters burn surprisingly clean, forget about sweeping the chimney twice each season.
Power of these heaters into the room isn't high, the trick is the constant dissipation of gentle radiation.
Mark Twain said something
about these heaters.
Keeping room A on a steady temperature won't be easy, since it's a small room. On a technical level, the heating demand is ideal for a pure mass heater. Maybe a small one, like a 4" or 5" mass heater in the room itself might do the trick.
One design that's particular good in burning efficiently is the batch box rocket heater, see
https://batchrocket.eu/en/
Lots of experience has been built up with these heater cores, so it's quite well known how to operate these, what comes out and, most importantly, why it is working like it does. Regarding tending, this is close to ideal: fill the firebox, light on top of the pile, close its door and walk away. Come back in an hour or an hour and a half and close the air inlet. For room E a sidewinder might fit the bill.