If the wood is really porous I will do one coat, then sand back down to bare wood with 320 or 400 grit. That will make the CA act as a grain filler. Then start building finish.
I normally don't wet sand until I'm done with applying CA. Depending on the call I usually do anywhere from 7-15 coats. The cocobolo call above was closer to 15, but I wanted the finish to look thick. The little lines you're seeing can be wet sanded out at the end of the process, but don't go coarser than 1200. Keep it really, really, really wet too.
Inside my calls' barrels I use a wooden-stick q-tip like they have at the doctors office to apply a thin coat of CA. I'll do more in the visible parts at the end. I usually do not wet sand inside the call, as it looks fine without it.
The best tip I can give is to apply the CA to the wood with no friction. Let the drop flow off the towel onto the wood, and move FAST.
I do not put CA over another finish in most cases. If you use japan dryer in BLO you can do that, but I don't see the point.
You can use micro mesh in lieu of a Beall buffer. Go all the way to 12000 grit and keep it cool or you'll have issues. I'd highly recommend a buffer....PSI has one for under $50 intended for pens, and it has two wheels. One for tripoli and one for white diamond. That way you can take a CA finish from wet sanding at 2000 grit to a perfect shine in seconds. Well worth it.
IMHO, there are a million different oils that you can put on wood and consider them "protected"...BLO, teak oil, linseed oil, tung oil, etc. They'll for the most part protect the wood from water soaking in, but a hard "shell" finish is much more durable long term. BLO has been used on walnut calls since the old days, but you should SOAK the wood in it for a couple days to fully impregnate it. A simple coat of oil does very little to resist the elements. Just one guy's (experienced) opinion. Opinions do vary amongst callmakers.