I'm sure you meant .2 and .4 needles and nozzle sets. I just want to say Congrats on the airbrush and wish you many many happy years with it ! I've had my Badger 200 for about 45 years now, it feels like an old friend. That's how they can get to be when you get used to them.
FWIW, I personally wouldn't put acrylic varnish of any brand over lacquer. There may be good reasons to do that but when I use lacquer I do it for the look of lacquer.
Edit: Greg's post reminded me that I didn't address the nozzle situation in my reply. I too would use the .4 day in and day out and for painting in general. I actually keep the .5 on my Badger as the resident nozzle combo. I have a .25 for that brush and use it now and then with very thinned down paint, it gives a very smooth/fine dot pattern which is good for some things. I'm sure all the more so a .2.