We know they rats were living in the walls so the insulation needs to be replaced and that's probable why the electrical was problematic.

Long term value creation and insulation is a diff metric- if you compare the above to prices in the peninsula they didn't see nearly the drop the rest of the country did.  

The best thing you can do is address insulation and make sure doors and windows are sealed.  

When the drywall comes off you should see if you need any spray behind that...could also turn the insulation different colors.

Dangerous with insulation.

I imagine all someone would find is ancient insulation. 

Shingles, 6x6 floor tiles, pipe insulation, countertops.  

I have a no pets policy for my rental, a one bedroom apartment that is an ADU on the bottom floor of a larger house that is a separate rental above, because there is less insulation between the walls, and the noise carries and barking could disrupt the other tenants.

I have a couple pairs of insulated pliers that just have a coating on the handle.

While Rhode Island Energy will subsidize smaller improvements (e.g. a new Google Nest Thermostat is $75 off), RI and RISE can either directly subsidize or provide you with the info to subsidize new windows, solar, blow-in insulation and more.