I would speak to an architect and permit department to see if its buildable 

If developing, you will need a full team for entitlements and permitting (civil engineer, survey, architect, etc.).  

I have started to work directly with the city to get approval to construct multiple duplexes on the property, a surveyor/engineer, and an architect finishing the plans.

A super ball number to get you going would be at least $190/SF-$220/sf ish... to figure out square footage it's probably best to connect with a Chicago architect like @Samuel Pavlovcik or @Prashanth Mahakali both can talk through the zoning and plan development process.

And exciting and for the very few that can pull it off can be quite financially rewarding.. you don't need architect type skills that's not needed until your actually going to build in most cases.. what you need is land planning Zoning city politics and it helps to understand basic underground construction .. but you don't need to be an engineer or especially an Architect to pull these deals off..

Maybe with an architect.

Your architect should be specifying these requirements and should be able to give you the code sections.

We're in search of a licensed engineer or architect to prepare a plan for a backflow prevention device in NYC.

From what I have researched, and from what the Modular architects/manufacturers/contractors have told me, there is no difference in valuation if it is permitted and receives its CO as a permanent structure. 

Cultivating relationships with architects, builders, and luxury real estate agents can unlock unparalleled opportunities in infill development, land subdivision, and tear-down projects.However, navigating this market requires a keen understanding of land valuation.