I am more or less stuck at this very stage on my build. So I will pass my insight of my bus deconstruction.
1) if you have access to a air hammer and air compressor get you one... even a cheap one. I had the side walls of my bus done in 2 evenings ... probably a total of an hour in shearing off the rivet heads.
2) My 1983 ward had some chicken s batt insulation in the walls. Most of it had broken down and was a lot of dust. So use a mask. I did not find much rust but again I think this is a situation of where you live more than anything.
3) Thermal breaks are great but cant always happen. To me and this is my opinion... I think being air tight is the next best thing. Most buses has so many air leaks its not funny. So to me sealing up with some type of vapor seal is what I am planning. Then I will pack mine full of 3 inch poly iso insulation then... some type of wall material.....probably Luan.
I am really hoping this makes it more quiet and more comfortable. In the past I got a hip shot quote to have it spray foamed with close cell insulation and it was close to 1200.00. not going to happen cause I only paid 1300 for the bus?
But the best bit of advice I can over from my experience is get access to an air compressor and a air hammer.
Here is the first panel I pulled.....
Ill see if I can get a pic of its current state. I have the large 4x8 sheets of insulation in it so its kind of blocking the view.
Hope this helps