Maybe appliances too, depending....Make sure to add lighting, it's cheap and adds a lot - cans in the ceiling and under cabinet strips.Note: you will probably need to add a few electrical circuits.....current code requires a lot of appliances to have a dedicated circuit.

Also not sure what year this building was built make sure to account for new code requirements.

You know tax  code written by the rich for the rich. 

owner abandoned home & codes letters on door How did you finance this deal?

Proper identification of tenants is also needed if you want any chance of having local code enforcement write tickets against the tenant and not the owner.Any Legal Action Documents: you’ll definitely want to know if the current landlord is evicting or suing the current tenant(s).

If more than two steps, code calls for it.

I will double check though with code enforcement before any work is even quoted.   

If 'duplexes' are selling for $X I'd want probably 10-15% off of X to cover the risk I'm taking and eventually the cost of converting it to SFR if I had issues with code etc.

I'd stay out of 53206 zip code.

Yes, people still operate them but one noisy neighbor and code enforcement can turn your investment into a nightmare.