There's really four sections for housing in the city. 1) Old Laqueta, which is small and populated by the upper class (who don't have their own private airships and docks), the Manifold, which is the wood and steel rigging holding the entire city together (biggest section), the Shell, the near-vertical outside of the old city which is where flight-capable races live (harpies, made into a player race in this setting, are a fairly large minority in the city, about 5000 strong), and the carrier-towns, where the really low-class live. Those support at least a third of the population on their own.
Funny you mention feather fall, since minor magic items are a major industry in New Laqueta. Specifically, there is at least one sweatshop that churns out talismans of beneficial winds, a normally 50-gold piece item that is an expendable feather fall item. Richer families go for the greater one that is 1/day, or even spring for snapleafs.