Are there any tricks to using CA glue? I know that it comes in different viscosities, and that's about it

I have seen some people use CA glue to hold veneer in the fret slots. Also seen people use Titebond. I am guessing that CA is better since Titebond may cause the wood to swell. also guessing that this should be low viscosity CA so that it wicks down into the slot.

I have also seen differences in what people use (or don't use) on the fingerboard. I won't use Epoxy. Trying to remain as non-toxic as possible. The main alternative seems to be using CA glue again. It *looks* low viscosity on the YouTube vids...but I am not sure. Anyone know?

The other thing I have seen used is just block oil. I am sort of inclined to do that. Partly because many of the folks who talk about wear on the fingerboard indicate that they have been using round wound strings. I'll be using flat, tape-wound strings, so maybe I will have less of a problem with this. My old string bass didn't have finish on the fingerboard that I recall, and it's strings were metal flatwounds. Would this make sense? If it wears too quickly, I figure I could always re-sand and seal with CA...

Thanks in advance!