If I wanted to insulate an existing house once and for all, here's what I would do:
Dig down to the footings. Redo drain tile if needed. Add 4" Styrofoam to the outside of the basement walls, 6" if I was really ambitious. Seal all openings to the outside. Backfill. Your basement will now be warm, so will not condense and turn into a swamp in summer.
Dig out the basement floor. Add 4" foam, then concrete on top. This step can be done any time.
Strip off the siding. Add 4" or 6" polyiso (foil face) to the outside. Caulk/foam and tape all joints. Stagger the joints. Add vertical strapping, and new siding.
Frame in the window openings, and install new efficient windows centered in the foam.
Go into the attic. Seal all openings to heated space. Then strip out the insulation, and have a foam contractor foam everything with at least 1" of closed cell foam. Then blow in two to three feet of blow in insulation.
That should get the heat loss down to less than 15,000 BTUH at -20 deg F outside AND make it completely comfortable inside. Even at below zero temperature with a howling wind.
Your problem will then be how to find a heating system small enough to properly heat it.
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