I’m practicing finishing techniques while my guitar is being shipped. I’m using flamed maple veneered plywood. I would like to exaggerate the contrast and have been applying a lighter color over a darker color to achieve that effect. I’m using water based dyes.

1) Does the color coat need to be cleaned or treated prior to next step? My colored samples have a chalky surface. Should I wipe with Naptha or something?

2) For fillers, do I apply before or after staining? If I apply before it seems it might require more sanding of the thin veneer, and maybe affect the way the wood absorbs the color? I read not to use sanding sealer - what fillers should I be using?

3) Besides Tru Oil, are there any other non-yellowing topcoats worth considering?

Thanks for your help. I tried searching but most results seem to be about nitro finishes, lacquer, natural finishes, etc.