Our value add was adding an additional bedroom without increasing the square footage of the home.

The costs associated are going to depend on what your building and square footage of your duplexes, as that will affect cost. 

I was thinking billing based on sq footage & location in bldg.

Does a finished basement count as added sq footage vs unfinshed.

This would give more square footage to the property. 

How do you calculate 50%, by square footage, or is it 1 commercial unit vs. 2 residential, so residential as the primary use wins?

Each building  will require its own property insurance policy, but interestingly (at least in Florida), you only have to have liability insurance on one building… it seems the entire parcel is covered.As for valuation, just look at other nearby duplexes and base your valuation on square footage.  

What is the property type, condition, location, and square footage?

(Praise God)-Mortgage will be around $2500 a month -AirDnA data was showing for homes with similar square footage and sleeping 8 people like mine would it would generate minimum of around $40,000 of income per year and this home BLOWS those other homes out of the water.My questions are: -Is this a deal you would do? 

If you live in a single family then move to a 4 unit and you're downgrading your quality of living in square footage, ect.