I have an option to take over owner carried financing of the building  that the previous owner has set up with the owner before them.

If this property were to make $225k without the additions based on its size and location, would it be worth it given the capital cost?

Just toss all the interior items - it is not worth the time and opportunity cost.

Should I set up an LLC for Airbnb for protection?

I have attached a spreadsheet I've created on the following cost of developing a duplex.

Normally, doing the work yourself seems like you are saving money, but it actually may be costing you more if you factor in time. 

The frustration of managing 28 locks, each plagued by the same problem, has underscored the need for a more robust and reliable smart lock solution.In summary, the Yale Assure 2 locks have proven to be a costly disappointment, especially when multiplied across 28 units.

We know we still have to pay for a property manager as well as we are out of state in Michigan and other operating cost along with utilities.

The example above is a very minor cost.

We've all seen the potential benefits: faster construction, potentially lower costs, and the ability to design unique living spaces.