I don't know anything about a home inspection and a lot of the stuff just flew over my head. 

We found out through a previous inspection report ( two years back) on the house we are interested in, that the roof/HVAC (heater/cooling unit/condenser etc) are all nearing the end of their service life.

I am thinking we as landlords can do the following but I am not even sure if that is enough to get landlords off the hook if a gas explosion does happen:- hire a licensed plumber to inspect for gas leak and gas pressure on an annual basis-install a gas leak detector or alarm in the rental unit-spell out in lease agreement that tenant is prohibited from removing the gas leak detector and tenant must notify landlord immediately if at any point the detector stops working-do semi annual walk through inspection of the rental unit to make sure the gas leak alarm stays installed and is working properly and that the gas stove is working properly.Is there anything else we as landlords can do to minimize our exposure to being sued in the event of a gas explosion in the rental unit ?????  

I had a home under contract in Hudson county two years ago, and in the inspection an oil tank was found. 

What kind of inspections did you get prior to closing/during the inspection period?

We had to fire a real estate agent because she was moving too slowly + lacked negotiation tenacity and it caused us to miss out on deals.Once under contract, you can also negotiate further depending on how inspections of the property come back and also appraisals.

Had it inspected and so far there's not a lot of work that needs to be done.

I wasn't sure if I should just stop the pet fee or ask to do an inspection to make sure the pet didn't damage anything.  

Looking to purchase a SFR and got the home inspection report back.

I would get a thorough inspection of the property to see if it is worth my time, effort, and investment.