You'll probably get lots of good answers since many of these questions are subjective. I can share my own opinions, but they should not be taken as gospel, nor should anyone else's. There's an element of experimentation and finding what you like here.
1. I drill all blanks (wood, acrylic, stabilized, whatever) at the lowest speed my lathe will go, which is 500 RPM. I turn at about 1800 RPM until round, then increase to about 2700 RPM for the remainder of the shaping. I sand and do all finishing steps at about 800 RPM.
2. CA glue for my money. Though to be fair, CA glue is my favorite finishing method for pens of any material, with the possible exception of pure acrylic/plastic blanks that can be polished to essentially the same level of gloss without putting CA glue over the top first.
3. I usually insert a "void filling" step in between the end of shaping with tools and the beginning of sanding, if I have any voids.
4. If it's stabilized, you probably have nothing to worry about. With unstabilized burls (especially very low density ones like buckeye burl), I will often use slower speeds throughout the shaping process and lighter cuts, compared to a standard hardwood like cherry or walnut. I'll also mention that it's really worth having a very sharp skew tool and learning how to make good finishing cuts with it when you're working with crazy grain like burl. Minimizes tearout potential, and saves some time in sanding - when I final turn with gouges, I usually have to start sanding at 180 grit. When I do a decent finishing cut with my skew, I can usually start sanding at 220, 320, or even 400.
5. CA finishing processes are about as personal as fingerprints, it seems. I'll share the short version of what works well for me:
- Shape workpiece
- Sand through 600 grit dry
- Clean workpiece with denatured alcohol
- Wipe on a generous coat of BLO
- Wait 15 minutes
- Wipe off excess and burnish with shop towel until dry (this burnishing step I will sometimes do at a higher speed than the 800 RPM I mentioned above)
- Apply 8 coats of medium CA glue with shop towel. I should mention I'm using some kind of cheap generic CA ("Magic Chems" brand from Amazon) and it has been working fine.
- Flatten CA with 600 grit paper wet until no more low spots are visible
- Polish with Dr. Kirk's scratch-free
- Polish with Dr. Kirk's micro magic waxes (#1, #2, and #3)
- Polish with Novus #2 and Novus #1
- Apply a coat of Renaissance wax to help repel fingerprints
This process results in an ultra-high gloss that is at least as good as I could ever get with MicroMesh wet sanding in the past, but it's much easier to use the wax-type abrasives IMO. The BLO underneath seems to really enhance the depth of the grain, and set off any chatoyance that was in the piece.
I find that the final quality of a CA finish is directly proportional to the amount of time, effort, and attention to detail I put into ensuring that you've eliminated ALL scratches from each step before moving to the next. That goes for sanding the wood as well as sanding/polishing the CA. I regularly spend more time on my sanding and finishing than I do on the rest of the pen turning process combined. It's so easy to miss little scratches left here and there along the way, and they
will show up in the final product if you don't eliminate them as you go. The specific nature of the abrasives is probably less important than just... spending a lot of time closely inspecting your surface with a bright light before you move on to the next finer abrasive. It's not that hard to manually sand out a radial scratch left by the 400 grit paper, by sanding longitudinally with the same 400 grit paper. It's significantly harder to do so with 600 grit paper. By the time you're trying to remove 600 grit scratches with polishing compound, it just doesn't work at all.
