For $20k that cannot be a heated garage unit... with a kitchen and bathroom. 

I called the County and there seem to be not permits for the unfinished large room, bathroom and laundry room on the ground level, but for a new slab and underground plumbing from 2005.We are thinking of buying the house and creating a studio on the ground floor and renting it out to a tenant.We have never dealt with permits, and we would probably hire a licensed contractor for the electricity, plumbing, heating, floors, walls and windows, but would do the rest ourselves. 

There was no heat , so we slept in sleeping bags . there was no insulation , but dad added it later .  

There are some costs in a SFR that can get passed to the renter, water fees, in some cases condo fees include heat (heating costs are lower when the tenant is writing the check each month vs turning up temp when it's cold outside), yard maintenance etc.

@Tommy Dang I would not bother upgrading the heating system to sell.

He gave me the typical MLS sheets that have the MLS number, a picture on the Left Upper corner, and all the details on Taxes, Sq Ft, Flood Zone, Zoning, Heat type, sewer, water, parking, etc, etc and it even has the paper clip link with Deed, Seller Disclosure, maps, additional pictures BUT there is no indication or note of co-broke fee in it. 

What are the unmaintained/older mechanical systems that may need replacement soon,    How are the utilities /heat set up?

If there's a common heating system for the entire building (or multiple units within it), that would be an additional expense for you.

For crime always like to check the Trulia heat map and BestPlaces.net. as well as driving the neighborhood.

I would be inclined attempt to work with him as he is in place and it will save me some money to do so, and he at least has earned the opportunity to make it work...just not at my expense.