Community: Energy efficiency and durability

Built the dream log home and now face the heating nightmare in Climate Zone 7. A masonry heater reduces the heating load of my in-floor heating system by half but without it my heating bills avg $500/mo. Here is my wild idea to reduce heat loss:

1/2" or 1" rigid foam against interior of perimeter log walls
Log siding nailed against rigid foam

Has anyone ever seen an analysis that indicates the benefit of having an air source heatpump run more before the nightly temperature drop in order to obtain a higher COP than later in the night?

A similar pre-charge could be done for cooling before the outside temp rose a lot.

In the past with leaky poorly insulated houses I don't think this made much sense, but now with some very tight and well insulated houses I belive it would be beneficial.

The main trick is to mine weather report data and control the thermostat based on COP curve, energy loss rate, and heat schedule.

Our den is extremely cold and have discovered that the roof has no insulation. Very thin bat insulation exists on the ceiling itself. This we found out when handyman took a look through one of the high hats.

Considering blown cellulose insulation so we don't destroy the Sheetrock, but I am concerned that its particles will come out thru the high hats and ceiling fan and will breath them. No estimate.

I've seen many references, here and elsewhere, to how vinyl windows don't last very long, especially cheap ones. Well, I have cheap vinyl windows from the early 90's and it's not clear to me that there is any problem with them, other than weatherstripping and looking less than glamorous.

So, how does a vinyl window go bad? Does the plastic literally just crack and break apart?

Is it the seals? Don't seals go bad regardless of the window frame material? And the glass can be replaced anyway.

I want to know what to look out for.