In some cases if the deal is really good, the majority of the funds will be covered.

LOC's can be great ways to do the down payment on a property while keeping your 20k cash liquid to cover repairs etc.

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.

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.

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.