Wianno, I don't think I was recommending wind barrier over vapor barrier under your joists. If I did, it was in error. Moisture/vapor retarder sheets on the ground under the house. Wind barrier stapled (or something) to the bottom of the floor joists. Insulation between the floor joists. (As much as will fit.) I wouldn't spray anything on the walls, except to try and patch a discrete hole (like where the electric line was punched, through) on the rubble walls. As Sharon said, anything sprayed (expanding foam, etc) has the possibility of damaging the stacking of the stones, causing settling and cracking. In some cases a careful re-pointing job might help, assuming your rubble wasn't dry laid in the first place. A dry laid rubble is helping to preserve your house from moisture and vapor being trapped under the house. Be very cautious about interrupting this cycle. Don't worry about the wind whistling through the rubble under your floors. If you have carefully insulated and sealed between the floor joists and at the sills, that's the best you can do. If you have pipes in this unheated space, re-route them before you block radiated heat from the structure with insulation. If you can't insulate the floor before winter, then, at least, insulate the pipes this year. But don't rely on pipe insulation in an otherwise unheated and insulated-from-the-living space area to keep the pipes from freezing. If you want to google for moisture/vapor barrier products, you'll probably find what I was suggesting. If I have a moment I'll go down and see if I can a get a tradename for you. Where are you? Molly~

I definitely want to keep things simple. I was aware of the zipR shearing but I have heard it is typically cheaper to use regular zip board and a separate rigid foam. I don't like house wrap because I think 90% of the residential house wrap is not installed per manufacturers recommendations. I work commercial construction and have seen the tyvek required installation methods and rarely see that in the residential market here. I also thought I could save money and give me the piece of mind by taping the seams myself. I will look into the price difference on the zip sheathing and separate foam and the R-zip. Might be the way to go if it is minimal difference.

Old wiring a problem and need to be careful, but should be able to blow in insulation at least in some areas. This requires making some small holes in siding and pumping in insulation material, then patching holes. Note that, assuming heat is running to achieve a fixed temperature, the decision on various forms of insulation is independent of other things done. There is still a benefit in storm windows or double pane glass even if walls are poorly insulated. Insulting roof or attic floor, if not done already, well worth it even if walls poorly insulated. In the extreme case, it makes just as much sense to insulate one wall even if the other three walls of the space are just plastic sheets. It sounds counter intuitive, but if the furnace is pumping out enough heat to maintain a fixed temperature in the room, the rate of heat loss though any wall surface is independent of the rate of heat loss of the other walls! Solar is a high up front cost item. Not worth doing if it means sacrificing funds that could improve insulation or replace unsafe wiring. Difficulty of redoing wiring depends on whether there is an unfinished attic and/or basement. If so, most new wiring can run through unfinished space and then fished up/down wall cavities to specific outlets/lights. Particularly if doing it yourself, electrical upgrades can be done piecemeal. Start with a new main electrical panel replacing the existing fusebox (if applicable). Then as time and money permits, run new romex cable from the panel to existing outlet locations in an area and replace outlets with modern grounded type. Outlets are quite cheap. The real cost is the labor. If you need to hire an electrician, this job is best done all at once. Experienced electricians are good at fishing wire through walls with no/minimal disruption of existing wall surfaces. The biggest problem is if a complete requiring requires bringing the house into current code compliance, since that would require adding lots of new outlets to meet current standards of outlet spacing

I'm in the northeast with a house that has the same combination of cathedral ceiling and attic spaces. Our problems are probably yours times 100. I agonized for a year over how to re-roof and insulate, and ended up going with the smartest roofer I interviewed who said, basically, you are far better off spending money on circulating air with fans than in trying to improve the insulation in the roof. I don't know if this is at all relevant to your situation, but at least it should make you feel better. I mean, how bad can your temperature shifts be in Hawaii??