Painting Platic on glow plane
#2

As a rule, no. There are some potential exceptions. Some of the automotive restoration places sell 2K rattle can paints that have a cross linker in them. You may or may not be able to match the color that you want. Some people have used Rustoleum brand enamel. My understanding is that it needs to dry for a couple of weeks for best fuel resistance. It probably wont hold up well to raw fuel though. I would test both of these options before committing to painting that rare, unobtainable cowl. Brushing on butyrate dope is still an option. Sig is kind of in flux right now but they do show some colors in stock. Brodak also sells dope. Your best bet may be an inexpensive hobby airbrush. My local farm supply store sells enamel paint that is fuel proof with the addition of an optional cross linker. It doesn't dry very fast ( in fact it is slow as Christmas) but it is fuel proof once it comes to full hardness. If you spring for the airbrush, a good auto paint supply store can sell amounts as small as a pint or half pint. This is the most expensive option but it will also be durable and they can get at least a close match to your desired color.
#4

2-part auto acrylics/epoxy paint (or 2-part boat paint) are the only two type of paints that stand glow fuel for any lenght of time.
The auto variant has to be sprayed on using compressor, airgun, paper filters and ventilationmask but there are 2-part acrylics that can be bought in rattle cans. The 2part boat paint could be prayed on but you can brush it on too but it is soo "sticky" to use compared to the automotive acrylicts and also heavier and you cannot polish it to a mirror finnish that you can with 2-part automotive acrylics.

Curare
The auto variant has to be sprayed on using compressor, airgun, paper filters and ventilationmask but there are 2-part acrylics that can be bought in rattle cans. The 2part boat paint could be prayed on but you can brush it on too but it is soo "sticky" to use compared to the automotive acrylicts and also heavier and you cannot polish it to a mirror finnish that you can with 2-part automotive acrylics.

Curare