Re: cold walls
My first thought would be to fasten 2" foam insulation board directly to the existing plaster, then plastering over that (or using DryVit). A lot of work, and it may take many years to recoup the costs in energy savings, but it will make the house more comfortable.
The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.