Should we insulate/air-seal a damp stone basement during renovation, or wait? – GreenBuildingAdvisor

We are renovating a 1914 bungalow in coastal Maine. The house is currently opened up to the studs, so we are making final decisions about insulation and air sealing. I’m looking for advice on whether we should address the basement now as part of the renovation, or leave it mostly uninsulated for the time being and monitor it after other work is complete.

Basement conditions:

• Stacked granite stone and mortar foundation, roughly 7′ high.
• Walls are very thick in places, up to about 18″.
• Some areas of the foundation are irregular enough that the perimeter beam/sill plate is difficult to access.
• Walls are not flat; there are ledges/reverse-footer-like areas.
• A large piece of ledge spans the width of the house, and one side of the foundation appears to be built on it.
• I occasionally see damp soil on the ledge, but I have not seen standing water. No sump pump or perimeter drainage that I know of.
• Basement floor is a mix of concrete slab, exposed ledge, and a patch of soil.
• Basement humidity hovers around 60-70% humidity in the summer. The rest of the season it is generally around 30–60%.
• Perimeter beam/sill moisture readings have been around 14% in the shoulder seasons.
• Existing framing is old, resinous, and appears to be in good condition.
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Known issues we need to address:

1. Critter entry:
   
   The house has had squirrel/mouse issues. There are several areas in the foundation where daylight is visible, so repointing/sealing those gaps is a priority.
2. Radon:
   
   The house has radon, and we plan to hire a radon contractor during the renovation. I assume this may involve some kind of poly barrier over the mixed floor/ledge/soil areas, possibly tied into active sub-membrane depressurization, but we have not finalized the design yet.
3. Basement insulation/air sealing:
   
   An insulation contractor and an energy auditor have recommended spray foam at the basement/sill area. I’m hesitant because the existing lumber is in good shape, the foundation may need future repointing, and I’m not fully confident that we understand all seasonal moisture behavior yet.

Main question:

Given this type of old coastal Maine stone foundation, would you insulate and air-seal the basement/sill area now while the house is open, or would you handle critter sealing and radon first, leave the basement mostly uninsulated, and monitor moisture conditions for a few years?

It would be helpful to hear from New England basement owners who have dealt with similar situations. Do I have any blind spots in my thinking? Are there any successful approaches, lessons learned, or products you would recommend using—or avoiding—that might help guide our order of operations?