I am thinking of using window ptac units for both heating and cooling. 

This will be used for repair cost and down paymentAny advices going forward?

We have started to think about selling the property and using the proceeds to buy another home in a more desirable area where we believe market and rent appreciation has greater potential for growth.

I am not sure I buy that Pilsen is the one southside of Chicago neighborhood driving rent increases, but it is surely a gentrifying area and factor.I think Bronzevilles & Woodlawn's ability to have more new developments has allowed that entire se coordinator to become a huge factor on the southside.Regardless, whatever you are doing is working so keep doing it!

They may think I am clueless to market rent, but I do not give a $hit. 

I need it to work as a quadplex so moving forward, I would appreciate not getting warning posts about zoning.Should I rent it as 2 units and put people on the same lease but keep their residences separate with a door that can just stay locked or something?

I think it really depends on your market and skillset at to where you want to start.

This isn't the same as liability protection, but I would think they would operate similarly.

I was thinking about Ohio.   

Followed up with @Alice Horn and looking forward to diving into the search!