So far I have run through a max of 2.5 5 gallon tanks in a season.

Your roof is a giant water collector and during a hard rain you have literally hundreds of gallons of water shooting out of the downspouts (you are right to worry about spring).

I am planning to charge him for the two 5 gallon buckets of Kilz primer that I had to paint the walls/ceilings with.

The paint cost me $80 per gallon, for each color. 

Ekopel 2k is like getting a gallon of paint, mix it for 10 minutes and you just pour around your tub and it's self leveling.

Goof Off, in gallon cans, probably would dissolve the adhesive, but it's very smelly and you'd have to set up some extra ventilation before starting.

That gas is from a 500 gallon talk on site, which gets topped off monthly from the gas company. 

Wear and Tear" is different than "Tenant Damage".A family in a house for a few years with worn carpets = wear and tear.A family in a house for a few years with a gallon of paint spilled on the carpet is tenant damage.Things wear out from use, expect that, it's a cost of doing business, but actual damage they should pay for.Just my thoughts.Good Luck!

Good thing with 87 bedrooms.I store the unused gallons/pails under the places for touch-up later. 

I went ahead and performed the tasks but was only looking at being out a gallon of paint, 2 connectors and a rod.