I found some stuff at PA in the back where you are not normally allowed. Had to go to the very back around the corner to find the scratch and dent stuff. I paid $100 for what would normally cost about $800-1000. Calgary North.
I'd be inclined to use a 7.25" skill saw with a metal blade. I have used regular 40 tooth carbide blades in a pinch but the teeth like to fly off. Wear gloves and a full face shield in either case.
I'm invested in ryobi for decades now. The small batteries are garbage imo, but the 4.0ah are good. I bought into ryobi when they were the only tool maker that sold without battery and charger. I'm not sure how long the battery last for me...
I wrap my work compressor head with a battery heater in the winter. I've worked to -20C. I do the same with my propane tanks. I've used 100lb tanks down to - 37C that way.
You will get condensation on the interior of the steel. Can you pull the bubble wrap and use it on the inside as a vapor barrier after insulation? Also make sure no insulation is touching the steel if you can do so. And rockwool is better than fiberglass in this situation.
The cleaner will do nothing to cured foam. I've cleaned my guns several times after they have sat for months. It's not difficult if the gun was made to be cleaned. Cleaning is done by scraping and physical means of removal. The new guns seem to be made to be throw away. I havent tried to clean...