It would still be a good idea to have a real estate attorney to work deals through locally, but Anderson Advisers can set you up to make sure you are insulated from liability and/or totally protected from litigation should something go wrong in one of your investment properties.  

I don't think you can guestimate by rooms or square footage, structure, windows / doors & INSULATION are big factors that are very different from house to house, especially with different ages.

I am more fond of "wrapping" their mortgage to insulate against blow back. 

It is basically like having many companies under one roof, but each "series" has its own assets and liabilities and is insulated from the other properties.

Insulation - Most older homes lack insulation.

Has a HVAC installed In 2011 along with completely redone insulation in the attic. 

Gas is not run to the building, so converting would be cost prohibitive.I would plan on ordering an energy audit and insulating any problem areas to help control costs, but not sure how much this would really help.

We have our wall insulation and windows being delivered tomorrow. 

Looked in attic and had adequate insulation and no signs of water damage or termites.

Your idea may help a little but insulation is probably the best bet whether batt or blown in, anyway best of luck!