He bought a new house around 1995 and allowed one of his sons to live in it for several years, paying only to cover the mortgage.Subsequent to his son purchasing his own home approximately 2 years ago, the house has been mostly empty except for a few months when a family friend stayed in it and only paid to barely cover utilities.

I have replaced several million square feet of siding and have probably 3 to 4,000,000 ft.² of roofing  covered in Houston and surrounding areas.

In your description of the home you can put all of the improvements you are going to be making, and you can use representational photos as long as you label them as such.

You should have plenty of options for 10% down (covers the rehab as well), especially if you have 13 rentals already. 

I'd either up the price on their purchase or charge a higher listing fee to cover the costs associated with the program.

For the other items I am hoping the numbers r conservative enough to cover most expenses and I did not miss anything big.

They don't realize that they just totally undersold their home AND paid more than a Realtor would cost for full representation. 

I submitted an insurance claim and it was fully covered by the insurance. 

Sometimes the client covers expenses and my fees are paid at close. 

I would pull the cover off the a-coil and see what's going on in there.