I have paid water,gas and electric. 

besides the general walk through of each unit, I'm thinking i'll need to bring on specialists to check out big items including roof, ACs, water heater (one centralized gas unit for whole complex).

For example, oil and gas is even better. https://www.investopedia.com/articles/07/oil-tax-b...Another area is agriculture.I've heard that Steve Newlin is a good accountant in Chattanooga, but I haven't met or worked with him personally.

I worked as a property manager for a time (regular rentals - not VRBO style) and we had a client, Baker-Hughes, the worldwide oil & gas company.

How about water, electric, gas etc.? 

If you're cleaning the gas stove and you bump one of the knobs, odds are good you're going to smell gas. 

They are all on a single same water, electric, and gas meter, so utilities are included.

Looking at a deal at the moment for buy-hold, the house has heat oil and it may take about 8-10k to covert the home to Natural gas.

In-unit gas heaters. 

(Picture a standard 1950s-1980s tract house, 2 to 3 bedrooms, roughly 1000-1500 square feet, and a gas furnace... that house would have probably been born with a 100 amp service.)