These things can easily draw you into the drama and expand into a major issue in your life.

The amount of damages you can collect depends on the average useful life of that item.Example is that as a landlord you paint the walls every 5 years.If you have to repaint the walls after a tenant lived in the unit for 7 years than this would be considered "Normal Wear and Tear" and you deduct $0. 

I have an engineer that does phase one, site inspection, and cost reserve stable for one price.Cost for everything above is in the thousands on average.Even if NNN with no landlord responsibility we still get the inspection as part of DD process.If the tenant doesn't renew it is important to know right before the option period kicks in how much life is left on roof, mechanicals etc. as in addition to the TI costs to re-tenant you can get hit with a lot of other capital costs.Lender is going to order a PCR site inspection report whether the buyer wants to or not.

I live in FL so I know about having to use A\C year round.As you know people mention a brand and price but not model which will ultimately determine the total cost.I was in the exact same situation and due to the rusted coil tubing, and overall condition of the Air Handler decided for a total A\C replacement.Payne is considered "Builders Grade" lowest grade and some A\C guys argue not to install them because it reflects on their reputation when you have problems with the system.Look for the highest seer rated, quietest, best warranty HVAC that is fairly priced.The installer is a HUGE part of the HVAC's life span, along with your regular changing filters, cleaning coils when needed, cleaning drain lines and vacuuming dust out of the Air Handler Cabinet.

However, I would prefer not to lose my life savings and retirement funds because of one incident...with that being siad, is the thought of everything being taken from me if I don't have a separate entity just a beginners myth?

This will extend the life of the equipment. 

After numerous life difficulties she moved out of the home because "I wanted a house in another city" and just left this home.

It's a fun exercise to divide the replacement cost by your estimate of the items useful life to calc out how much you should theoretically have in your reserve fund each year.I'm a long ways from theoretical, but at least I know how far off I am.Best to you.

They were so attached to the house and they believed that we could give the house its new life.

If you ever get the chance to produce for them you might have a customer for life.