I agree, I would be very careful doing anything that is not permitted or allowed based on the zoning. 

What you would presumably do is find land, buy it, ask for a construction permit, hire an architect to make plans and hire a builder (the developer) for the construction.

I know certain areas where I live are limiting those types of permits, etc.

A key step is also meeting with the City and/or all entities who are involved in permitting. 

Costs like engineering and permitting can become disproportionately high for mid-size projects.Height and Density: Focus on areas where zoning allows for verticality and density.

As far as permits and renovations and ADU additions?

Can you take it to the city to get it permitted?

Just keep thorough records of your expenses—materials, labor, permits, etc.

All you're doing is finishing space and you should be able to go through normal permitting processes to get that done.  

The building is typically zoned and permitted for short term rental use, so there's very little chance you'd ever be banned from doing short term rentals if they crack down in that market (like they are cracking down in my market).Cons: They typically charge 25% (in my market, at least).