I feel like this deal pencils at $365-375k but need to add a bathroom, redo kitchen and existing bathroom, close in garage port for more sqft, + cosmetics and new appliances.

Try looking into zillow/Redfin and see what your potential rents you can get near the neighborhood by filtering the bedrooms/bathrooms of the intentional property that you are planning to buy.

The easiest way to avoid it is to include all services in the rent and estimate use for each unit, based on square footage or number of bedrooms, bathrooms, etc.  

I'd have to invest around $5,000 in new windows and some other capital, improvements like bathroom improvements, paint and texture.

So, I tried to help the situation by getting a contractor to go replace the floor and remodel the bathroom so that the house is nicer for her.

I'd have to invest around $5,000 in new windows and some other capital, improvements like bathroom improvements, paint and texture.

One bedroom (the master) and the upstairs bathroom, have no heat whatsoever though so space heaters have been used for them in the past.

The property is listed for $259,900 and needs new floors and updating to the kitchen and bathrooms.

We added value by re-doing the whole house, installed vinyl floorings, rebuilt 2 and a half bathrooms, re-painted the whole house, replaced all the hardware in the house, installed new lighting, ceiling fans, re-painted the kitchen, and completely remodeled the upstairs.

New flooring, kitchen, bathrooms, light fixtures, trim, doors, etc.