What that means is after a certain point in taking proper measures, the benefit that you get out of each additional measure starts to go down while the cost continues to go up.

If and when we move back to that first, what measures should we take to ensure and record that we are moving back to that home as our primary residence?

Great, I will add a small measurement of black pigment at no charge and continue to do so based on your feedback/photos/additional info.The folks at your paint store can be a great asset to you if you treat them like members of your team. 

1 - Retiring early isn't a goal since it isn't measurable. 

If you measure yourself they should come out and complete the install in a few hours. 

It takes a few hours to measure, look at product and price materials.

You should be confirming all the key elements of their application by phone or other measures that verify the information in their application is true.3) Get a good lease, legal in your state, that protects you as much as possible, particularly if you are in CA, which it appears you are. 

(measure twice, cut once) ;) Are you doing all the work or subbing it out?

Cap isn't a good measure of the return you'll receive especially since you use leverage (which is by design but often missed by most investors).  4.

You might look into some sort of measuring system for the heat.