ADA requirements for a garden-parlor level duplex

I’m looking to gut renovate a 4 story brownstone (garden, parlor, first, second) and convert it to a 3-family. The plan is to have the garden- and parlor-levels be a duplex apartment and each of the top-floors to be a floor-through apartment. As of March 2012 it seems the buildings department is enforcing the ADA requirements more strictly. In this case (a non-elevator bldg), 25% of the building (the garden-level) would need to be ADA compliant.  Two questions: A) If the parlor and garden floors are a duplex apartment, is it still only the garden-level that needs to be ADA compliant or would it have to be the whole apartment (eg both floors)? B) Does anyone have recent experience going to the mayor’s office for a waiver? Can you get one if you bring drawings showing that replacing the steps with a ramp would result in a too steep ramp? Thanks!