The laundry and icemaker valves require cutting the drywall to install the new "boxes" that surround them, but I've always had other drywall work to do anyway.

What's the cost per square foot installed?

There is low hanging fruit, like granny's garden window to install in her kitchen, charge her $500 for 2 hours work.There are hundreds of fix it guys, carpenters, roofers or construction types running around here, many think they can be a general contractor or go out on their own.

Many installment transactions carry no interest, just sounds like that is due to it being RE.

The rehab looks cosemtic mostly and because of my connections I can get the flooring installed for about 900 dollars (600sf total) and painting for probably about 500 just the inside.

But even I knew that replacing a roof, gutting/replacing a kitchen and two bathrooms, PLUS installing hardwood floors for only $18,000 was ridiculous. 

Take off that metal security door if its not needed. 

It is a slower installation, but by far the most cost effective...Removing and disposing of asbestos is where the cost is.

Are those something an investor could install themselves? 

I am pushing to get a split fence installed on the property - the yard is currently shared between both tenants who both have dogs, and I would like two separate fenced areas for them to let the dogs out without tying them.