I have to put a clear finish on my walnut guitar body. My luthier says I need to fill the grain with a clear product before applying nitro. I have been researching this, but as usual, I'm confused.

1. I thought I wanted a clear and colorless product, because I want the wood to show through, but now I'm reading that a little dye will make the grain pop out. Is that right? If so, what dye should I use?

2. I've seen lots of products recommended for filling. The two that stand out are shellac and epoxy. Shellac seems simpler, but a lot of people love epoxy, so there must be something to it. Which is better?

3. I believe my guitar has a few nearly microscopic holes in it where planing pulled on the figuring. I've seen superglue recommended for these holes. Is that the best way to go, or should I just keep applying filler until I get a flat surface? Also, will the little jars of acrylic glue work? They have nice thin application tubes that ought to be useful for applying tiny amounts of glue.