Make a floorplan. make 'to scale' miniature stoker-boilers, with doors for the ashpan and boiler cleanouts.. make a minature of the coal hopper.. then postion the pieces around to see what you think will work the best..
Measure the height of your tractor,, when dumping coal into a hopper,, and add plenty of extra.. there is no 'uglier' sound that that of a truss or rafter board cracking in two. [don't ask how I know that sound]
I'd suggest making a swing out 'chute' that is like a bottom-hinged door, that when open is a very wide chute, dumping into the coal hopper.. You open the chute/door, it's stopped by chains at the right angle.. you drive up to the chute with a loader-bucket of coal and dump it in,, most or at least a lot of the dust stays outside the building, if you seal off the hopper on the inside, allmost all of the dust will stay outside., then push or pull the door/chute closed untill the next loading.. just provide rain/freezing rain protection, to keep the hopper full of coal dry, and you are good to go.
I'd look into the idea of a conveyor for the ash pans.. leading to a door in the base of a wall.. have tracks with low carts on the tracks.. set the ashpans on the carts,, and roll them to the low door, and outside,, THEN empty the ashpans into the front end loader bucket,, and take to the next hole in the farm road to fill..
Provide a location for your remote generator, and bury power lines to the house when you bury your insulated Pex-Al-Pex tubing package. This will keep the noise, and smells of your backup genset from annoying you inside the house.
Bury extra control wires for relays, pumps, temp sensors etc.. wireless stuff is not all that reliable at 150'..
Provide windows with screens for warmer months to keep the room temperatures under controll, or install a cedar 'dry sauna' in the corner.
OK, my brain is tired..