I can go for a short drive and find entire neighborhoods that fit the 2% rule in my area, but I would never invest in this area unless I got an excellent price that allowed for a full redo of the plumbing/electrical/HVAC because the properties are old and undoubtedly have deferred maintenance; landlords/slumlords in the area have been known to do the work themselves; and I don't want to deal with countless minor maintenance issues (eg. leaking faucets, malfunctioning outlets, etc.) that are bound to arise in a property with old and/or shoddy plumbing/electrical/HVAC.I don't mean to sound harsh in any of my response.

My HVAC guy came today, he maintenanced the furnace, repaired the crooked chimney pipe and malfunctioning thermostat.

That being said it takes a specialist in most cases to determine what is needed for a slab on grade malfunction.

A home warranty usually responds to malfunctioning items, not items in need of upgrades.

Should i leave the appliances and replace them as they start to malfunction throughout my stay? 

I live in northern Minnesota... regularly 20-30 below zero.The house used to be heated with a natural gas hydronic boiler, the former owner was an electrician and I am thinking the boiler malfunctioned and instead of replacing it he installed electric baseboard heat instead.The pipes for the radiant heat are not hooked up in some areas.

(Unless equipment malfunction) so my employees are happier, the equipment doesn't work as hard, and my clients motive too.

My concern if I do decide to supply some or all of these items is that I would be liable if a fire extinguisher or escape ladder malfunctioned.

This typically comes from a malfunctioning furnace or hot water heater.  

It's oh so convenient that the outside unit 'undercharging' you is the malfunctioning one and not the meter inside overcharging you.Did you ask them to check for a leak on their side of the meter?