Best wishes for your new home. Right off the bat I would be inclined to replace the electric wall heaters with a propane gas fired forced air furnace. The feasibility and cost will be affected by whether ducts can be economically routed. One way is to obtain 2-smaller units and locate one downstairs (crawl space?) and the other in the attic. This would give you an efficient zoned system. The propane units will cost far less to operate than electrical units and much of the cost of establishing a tank and gas line may be subsidized by taking a contract with a local propane company. (They often set tanks and route gas lines without cost). This also sets you up for the future hot water and dryer.

Ask a local heating and cooling company to provide you a bid to see if this option, or one they might suggest, fits in your budget. It would be a far better investment to get an efficient comfortable and safe heating system in place rather than continue to renovate the electric units. And just think how much space you will recover without having to work around the wall heaters.

If money is an issue, A DIY option may be possible if you are knowlegable in routing electrical and gas lines, or even just the flex duct lines. If the hookups are already in place, and you route flex ducts, the furnace installation cost may be negligible. The furnace vendor / installer would provide equipment, and fabricate a connection plenum, mount the furnace, make connections, and hook up your flex ducts. Your work would probably save you at least 1/3 on overall cost.