Things like cracked window, not strapped water heater, missing smoke/fire alarms that the lender wanted rectified. 

I think in your situation you could charge an extra fee for the use of the w/d to cover the water usage

You may want to run the numbers again if you rehab the place for $12-15k and take care of the water heater, furnace, etc in that process.

One water heater will need replaced.

Unit 1 - Painted throughout, installed new floors throughout the downstairs, replaced appliances, kitchen cabinets, the bathroom vanity, the majority of the light fixtures, and the old dirty light switches and outlets.Unit 2 - Replaced water heater and rangeOther - Repaired roof, added some foundation supports, and added curb appeal by painting the patios/doors, replacing porch lights, and putting new house numbers on top of the paint What was the outcome?

Unit 1 - Painted throughout, installed new floors throughout the downstairs, replaced appliances, kitchen cabinets, the bathroom vanity, the majority of the light fixtures, and the old dirty light switches and outlets.Unit 2 - Replaced water heater and rangeOther - Repaired roof, added some foundation supports, and added curb appeal by painting the patios/doors, replacing porch lights, and putting new house numbers on top of the paint What was the outcome?

Unit 1 - Painted throughout, installed new floors throughout the downstairs, replaced appliances, kitchen cabinets, the bathroom vanity, the majority of the light fixtures, and the old dirty light switches and outlets.Unit 2 - Replaced water heater and rangeOther - Repaired roof, added some foundation supports, and added curb appeal by painting the patios/doors, replacing porch lights, and putting new house numbers on top of the paint What was the outcome?

Basically - all developer impact fees from a local agency (city, county,special district, water corporation) are removed if under 750 square ft

Water heater?

You can get it on amazon, dilute it with water in a pump sprayer and spray the baseboards on exterior walls, and spray around the outside walls on the house and you should be good to go.