Thanks for the reply. I knew the question of brick beauty would come up. For what it's worth, it's been painted (even more unfortunately they painted it red), and there's no consistency to the composition or technique in the mortar joints whatsoever. The basement is fieldstone, limestone specifically. It's actually kind of a weird setup, as I'm in the city and the east side is basically right up on the street. I'll try to find photos of that to help with the visual.
I had considered that insulation on the outside would require me to heat the walls still, but I'm doing that anyway. Also heating isn't my biggest concern, winters in St. Louis are usually mild. On sunny days above 35 degrees the heat doesn't kick on but a couple of times anyway. But during summer, when the nights are in the 70's the brick just absorbs so much solar energy during the day it doesn't really cool down well. Presumably exterior insulation would mitigate that, but it's very possible I'm overestimating how much of an effect it would have.
