1. I believe you can because most modern tung oils are compatible, they contain very little or no tung oil but a lot of lacquer blends
I would never again do an alder body in natural with tung oil, it turns into a terrible brownish color, like 70s desk tops that old crappy offices still use
You could use a dye and make it a little bit interesting, people like alcohol soluble dyes or aniline dyes.
2. the whole neck is sprayed and then the frets are polished, the lacquer does not like to stick to frets, even a fingernail will take it off. You could wax only the frets to further ease cleaning up
