The best defense against rats entering your property is to seal off all entry points (holes, cracks in walls), remove food sources (dirty dishes, food left in trash cans), and water sources (like leaks). 

I know it can feel like uncharted waters at first.

The current owner is letting me take over the property as a tenant as long as I pay the water bill and the mortgage payment on it and whenever I decide I can purchase property for the balance of the mortgage  they are in no hurry for me to purchase the home as long as the mortgage is paid. 

- Securing the property- Removing the waterIf your furnace was stolen, you may need to get propane heaters to facilitate water removal.

The other thing could be tracking what you have had come up on the last 5-10 projects after closing, i.e. the water heater was at the end of life when we bought the last 6 out of the last 10 properties.

They are full size and yet still run off 120v and just need a water source and drain. 

Instead, shut off the water to the toilet and place a sign on the door "Art exhibit: Non-functioning bathroom."

They'd also probably be more aware of how much water, gas, or electric they are using when they have to pay the bill after each cycle.  

Interested in getting some extra income with converting the extra space in the basement into a rentable unit.Basements in a one-family home can be lawfully rented only if the following conditions are met:Compliance with the Housing Maintenance Code for minimum room size.There is a minimum ceiling height of 7 ft.The walls, as high as ground level, must be damp- and water-proofed if HPD determines that subsoil conditions on the lot require it.The basement is occupied by one family and does not include boarders.Every room must have at least one window.The bottom of any yard or other required open space cannot be higher than six inches below the window sill of any required window in the room.

Due to this water being behind levees the water stayed up for 4 months.