I fear all the good points I may have made earlier are going to evaporate.
Your land design is great. your hone construction and parts of the design - oh dear.
Having been a general contractor for more than 45 years - I can't argue your observations about - skilled contractors. As for the "current year" IBC-IRC - it is there for reasons. Yes, scaled detailed blue prints submitted to development appeal "boards" especially in rural areas do frequently work with and accept "original" ideas that are different. Unfortunately, there is nothing original in your plans. Cheap, yes. Not economical - cheap ... and there are distinct differences. You have mentioned two occupants both with mobility and visual impairments - said impairments are escalating. This is not reflected in the house design particularly when it comes to emergency evacuation or providing the time to evacuate. You have mentioned the first physical structure burned for unknown reasons. The second structure, a single wide model home, due to electrical issues. Both structures burned "into the basement". This tells me a number of things. Firstly the house was occupied by a financially and time limited person or persons. The house probably burned due to faulty fireplace, wood stove or chimney issues. The electrical issues were probably related to overloaded circuits - possibly in the winter time when we all consume more energy. The other thing it screamed out was ... the fire department is NOT around the corner ... but rather like most rural areas they are volunteers and the fire hall is not close and response times are such that they contain not extinguish the fire(s).
Your home does not provide for restricted mobility exits. The lower 7 foot ceilings insure the reduction of breathable air in the event of a fire. Yes, "handicap" appliances are more than awkward, no question but there is a difference between awkward and ... lethal. Your current air flow design and methodology regardless of season - won't work in your favor when you most desperately need that air.
With everything attached to your home - garage, greenhouse, "elevated" deck - finding safe shelter in an emergency ... is non-existent. The barn is too far. Winter is when the most homes burn - physically handicapped, outside without proper clothing ... waiting for fire trucks is something you can't afford.
Your seven foot ceilings may provide minimal benefit but in actuality will impede air movement and, in the event of a fire, reduce breathable air due to the forced fire gas cloud expansion and reduce time available to evacuate. The reduction from 10+ foot ceilings to 8 foot ceilings is purely economical reasons directed towards the sawmills. The reduction from 8 foot ceilings to just under 8 foot is yet another move by sawmills to make more money. The "whatever year" IBC / IRC stopped further reductions in ceiling height due to the consequences of gases generated and/or created in open heated spaces.
And, I am sorry, but the basic construction material chosen for the house may provide slightly greater insulation values than a wood framed house with fiberglass batting but ... when heated, NOT IGNITED, the off gasses are lethal. Today, there is so much talk about insulation rates, vapor barrier sealing and costs it is a fertile ground for limited litigation lawyer-ed wording for product description.
The climate in Southern Missouri is, well to us Eskimos up north, just downright balmy. Balmy, though I might like it, isn't great. Firstly, you have humidity - moisture - wetness - and water. Each of these have different physical properties. Your main house construction material - Styrofoam - sucks up all three at incredibly fast rates. Draining and/ or drying takes so very much longer than the uptake. Once wet, unless removed to an isolated protected location, probably won't dry. And, when wet once, will absorb water/moisture even quicker with each successive opportunity. With the moisture comes swelling and the consequential loss of physical structural abilities. Mildew, mold, algae and other green through black life forms without legs love your weather. Check out the barn in corners sheltered from light - that's mold. Warm sunny corners - that is algae and/or mildew. And with your winters being so warm, it isn't cold enough to kill any of those life forms - they just go dormant. And the sealed house provides so many pockets for growth.
Your drawings are more focused on the slope of the property rather than prevailing wind direction and higher wind limits. Wind pushing snow or rain has a serious physical energy which takes a lot of strength to push aside or brute force to stand up to. An ability that is needed for decades and decades - not a couple of unpleasant winters.
Other suggestions would include separate the greenhouse from the home. This provides more options to develop uses and provide space to access different areas. Separate the garage from the house. Garages burn and all too often - take the house with them. And the cost to heat them is ... a financial hindrance. It is amazing the amount of materials that accumulate in a garage that are flammable or toxic whether liquid, solid, heated or ignited. And then there are the compound chemicals created with the introduction of heat.
As for low maintenance, there is nothing low maintenance about your design. Most, when it comes to maintenance, are invasive, which is another word for very expensive for experienced contractors and bankruptcy expensive when using causal labor. The elevated deck is a high maintenance item and a terrible heat robber from the house structure. If you had designed an attic, there would have been an enormous amount of heat to recycle. The other air movement paths ... may become expensive as most won't quite work out the way you have drawn and you may chose to try something different. Wheels under cabinets - is a great idea, seriously. But, unfortunately, is one of those ideas that develops issues over time. If on a wood floor - oh dear. If on a concrete floor, I hope it is a steal reinforced 3 to 4 inch slab without tiles or carpet. Otherwise the compression of a book case full of books rolling on two wheels probably less than 5" diameters exerts a serious amount of weight on an extremely small space - 1/4" by the width of the wheel. Most floors are 5/8" or less plywood. 550 pounds equals approximately 3.82 pounds per square inch based on 144 square inches per square foot. 550 pounds on .25 square inch equals 2,200. It's one of those "whatever year" IBC / IRC thingees.
There was mention of "building mass" being used to an advantage however, other than potentially a small amount of concrete floor which has not been defined as to measurement and density there is no building mass available for use. Building mass takes space, almost evasively so and an expensive square foot cast even for salvage DIY efforts. I learned this lesson the hard way a coupe of years ago.
After watching the house exterior wall video I finally noticed all those wonderful trees. They are going to affect the heat portion of the sun's rays striking the house walls. And then there is the greenhouse and how much it will be sheltered or affected by the trees - winter and summer.
And going back over the drawings there seems to be an absence of a spot or place within the home with a large window - possibly two - to sit and watch the world on days when walking through it isn't motivating enough.
It seems so much has been directed towards cost without consideration of consequences. How so much of that cost direction isn't providing you and your mom with comforts - creature or otherwise.
Compared to my first message, yes, this appears harshly negative. Your multiple reasons mentioned and not mentioned for disliking contractors are extremely valid without question or argument - but many of those concerns could be addressed with contract clauses and penalties. And, I can also see where a simple accident can have extremely unpleasant consequences for body and mind. Your thought processes are excellent, extensive and well connected to what is around you ... with the exception of you. Your pocket book may be attached to you - as is mine attached to me - BUT it is not you or your Mom! One of the problems of following the construction path you are on - there is no resource to fall back on if things go south. Unskilled labor does not have liability insurance, performance bonds or breadth of experience. And, if one of those development board personal doesn't like what is coming together - ahhh, the delays that can create are ... just plain nasty.
Firstly, I am only minutely younger than your mother. I have been extremely fortunate in that the accidents and injuries I have experienced on the way to here in my life I have healed from where many have not. You and I will never meet beyond what we have here - so, I have no gain being unkind without warrant-able reason. From what I have read of what you have written concerning ground water management - you are someone this world will miss and you are someone who has a great deal to contribute. I do not want your departure to happen any quicker than it should. It is the description of your home I have taken exception to - not the intent of the author nor the author!
I still bow to you and your contributions to all of us.