Most of the airbrush work in pinball restoration is dumping paint uniformly (and lightly!) onto a masked area. So I am not sure the quality of the airbrush is that important. I have been using a 0.5mm needle size since I am primarily trying to get even light coverage over a masked area.

I use an Iwata that I bought in a kit: https://www.iwata-airbrush.com/airbrush-sets-kits.html

As for paint, many people swear by Createx paint. I am using Golden High Flow due to the variety of colours and their online Golden Color Mixer.

You could get a cheap compressor for like $100 and a Neo for $60. Much cheaper this way and still gets the job done excellently. Just FYI for saving some dough

Be sure to get a moisture trap for your compressor line. I've had a Paasche double action since the 80s. It's a workhorse. I'm not sure how the current models compare, though.

If you are masking off and looking for an even coat, the cheapy HF kit is priced right:
https://www.harborfreight.com/quick-change-airbrush-kit-93506.html

If you're being more "artistic", it won't work, because it just blasts.

I recommend getting a gravity fed airbrush. They're around $20 on amazon. The syphon feed airbrush is going to give you more problems (viscosity of paint, air pressure settings, pick-up tube, etc). I'm sure others will have varying opinions, but I've used 3 different brand syphon style, and then switched to gravity, and won't be going back.

Your large air compressor will be just fine (although way overkill). You usually only need 20-40 psi for airbrush, and very little volume. As mentioned, get the moisture filter.

Gravity fed all the way

I use a harbor freight air brush compressor because its small, quite and has the water seperator that comes with it. https://www.harborfreight.com/1-5-hp-58-psi-compressor-and-airbrush-kit-95630.html
and a badger 150 air brush syphon type and never had a problem plus its easy to clean and change colors

On a slightly related note, has anyone figured out a way to reproduce the "zip tone" paint style where shading is achieved by using many small dots in varying densities to go darker or lighter?

I am afraid that you will have to resort to screen printing to have any hope of reproducing a decent halftone. Art supply stores used to sell dry transfer halftone sheets in various shades and gradients, but it only came in black (camera ready), and was very fragile.

Look at a Badger Sotar 2020. I use in my modeling and love it... nice adjustment on line width etc