My Badger 200 is a bottom feed and about 30 years old!
When I tweak the needle, I usually just open it a biit more. I find that using acrylics means thinning more and adjusting more to keep the paint flowing well.
I use Vallejo Air paints, but thin them to start with, can always add more paint if needed.
The Iwata is a superb piece of kit, can spray down to about 0.1mm. I have sprayed WW2 3 tone German camo freehand on 12mm tanks before.
But, as it was so expensive I tend to keep it for those 'special' jobs that need super fine work.
I started spraying with enamels, mainly because thats all there was back than! Main thing I like about them is they dont dry at the nozzle.
Yes the smell is grim, but I always wear a mask and spray in an outside shed anyway.
For solvent I use either whie spirit or cellulose thinners. Cellulose helps reduce the drying time.
I always clean with appropriate solvent ( Vallejo airbrush cleaner for acrylics, white spirirt for enamels) then strip down and use aersosol airbrush cleaner. Usually this is at the end os a session, not in between colours