Kitchen, flooring, bathrooms, paint, insulation, drywall, electrical, plumbing, new heating system, windows, doors What was the outcome?

I am in full agreement that a positive cash flow is a very important goal, due to the fact it insulates you from gambling on appreciation, equity, and rent increases. 

Is it pipe insulation, boiler insulation, some kind of blanket insulation?

No allowance for insulation or other thermal improvements - such as upgraded windows.  

And having a third (or fourth) mortgage would insulate you from "calls" on your LOC.

Through the program, the insulation is 90% off, and then I can take an additional $750 off for a knob / tube inspection.

What @Kevin Sobilo said, and also add insulation. 

That insulates me in a different way.9) You have to figure out your net worth to see what sort of umbrella insurance you should have on yourself as if something major happens and you have a decent net worth, you can bet your bottom dollar they are coming after you personally.   

To me it’s a myth that any thing low price is insulated from a downturn because “people need a place to live”.

If there's no rot, it is possible to pull out the drywall and insulation and dry the place out.