My best guess is that the white stuff is CA slurry that is created during wet sanding. You're not doing a grain fill (a couple coats of CA applied then sanded back down to bare wood) on that porous wood, and that porosity will absolutely telegraph through each coat of CA you apply. The slurry collects in the pores and when it dries out it shows up white. The slurry is a good thing, it should be expected. You just want to be able to wipe it off when you're done, and a non-porous finished surface is key to that.
Another thing that can happen with porous woods when you don't do a grain fill is the white diamond from the buffing wheel, if you use one, will collect in the pores and it is pretty much impossible to get out.
So basically a grain fill is a good idea on porous woods. Walnut needs it. So does hickory. Cocobolo doesn't. Neither does blackwood. And so on.
For me, a dozen coats of medium is pretty good. I rarely apply less than that. That being said, sanding at 600 will eat through 12 coats in no time. I start sanding at 1500 usually, and it isn't uncommon to sand through on an edge or contour. If I was starting at 600 or 800 I'd be back to dipping calls out of frustration. My advice is to dump the coarser grits and start at 1200. If you do a halfway decent job of applying the CA, 1200 and finer is all you'll need. And by all means get yourself some Satellite City non-cf activator and make your life easier.
I also wouldn't try to learn CA finishing on a wood that is kind of tough to finish. Try it on a piece of dense hardwood like cocobolo, get the hang of it and you'll then have an easier time with the tougher woods.
