Air sealing need to be at the top of the ceiling so you could remove boards to access around plumbing and light fixtures and what have you. Then if you remove a board every 2 ft or so you might get insulation under the floor and above it.
For storage you could build anther floor platform out of 2x8s and the salvaged boards.
The stairs are another problem likely not an exterior door at the bottom and un insulated walls .So maybe build small insulated room around the stair top with an exterior door and remove the lower door.
It looks like you do have high and low vents already.
For storage you could build anther floor platform out of 2x8s and the salvaged boards.
The stairs are another problem likely not an exterior door at the bottom and un insulated walls .So maybe build small insulated room around the stair top with an exterior door and remove the lower door.
It looks like you do have high and low vents already.