When we did have a Legitimate repair (hot water tank leak) the lazy x!

.- It might be a little, but you need to feel comfortable with what you do or you will tank, stressing about things.2.

Basic tool box/tool bag containing: cat-paw pry bar (I like the shark), hammer, tape, philips & flat head in 3 sizes each, couple of adjustable wrenches, wire cutters, channel locks, needle nose pliers, nail set, two pipe wrenches, multimeter (get a good one like a fluke and learn how to use it), electrical tape, teflon tape, sharpie, carpenter pencil, utility knife & spare blades, small handsaw, carpenter's square, small level, lightweight spackle, scraper, paint can opener (try to store leftover paint in a non-freezing space at the house where it is used), allen wrench & torque wrench multi-tool, pocket knife, and probably a couple things I can't think of off the top of my head.7.

Also, I don't know enough about real estate investment to invest that money wisely or with confidence yet, and would need to stick the proceeds into an index fund until I felt educated enough to wade into the shark infested waters.

The quickest way to tank a property is offer no-money-down move-in.Financially responsible tenants know how to budget so they are more likely to have cash on hand.  

If he asks what you are doing, reply with a short statement...fixing the hot water tank.

Charge them for the oil in the tank .

I will look into putting in electric heaters, putting in propane wall mounts, and getting separate boilers and oil tanks for each of the units.

A good way to figure this out is.....can you see and reach out and touch the heating system, the water tank, the electric panel, the utility shutoff valves ? 

So, you've been living there for 20 years, paid below market rates for the apartment, you've bought a new house you're moving to, and you want to extort more money out of your landlord to move, or deprive him of the ability to re-rent the apartment at a fair market rate, instead ensuring that any extra rent found goes in your pocket and not his.You sound fantastic.And they call landlords sharks.