Some questions about FDM printing

After years of resin printing I have been thinking about pulling the trigger on a FDM printer to make items that will physically wear better. I am looking at the new Centurie Carbon the Neptune 3 pro and the Neptune 4 and am trying to decide which to go with. AMS is not something I plan to use so that doesn't figure in.

So some questions. I have read about people doing .1 layer heights with .25 nozzles, how does that work? The Elegoo website only has .4 nozzels can you just by a 3rd party smaller one and use it? Is there a such thing as .1 nozzles? Are any of the 3 better at print detail?

I have read that enclosures with consistent heat are important, especially for materials like Nylon and Polycarbonate. Can you just put an open frame fliment printer like the Neptune 3 into an insulated box? Is the Centauris enclosure worth the extra money? Can they even use polycarbonate filament?

Lastly my wife hates the smell of resin printing, is FDM better with that? Does the enclosure on the Centaurie make any difference to smell?