If you want museum-quality, you'll definitely want to get beetles or maceration. You'll never come close to the same quality with the simmer method, but I think, for me anyway, I can certainly get "good enough". Especially good enough for free (or the cost of the whitener)
I've only done one myself, my buck last year, and this was my process. About to do my second this weekend. I'll do it about the same, but still not sure if I want to add anything to the water.
1) Definitely wrap the bases best you can to preserve color there. You'll probably still loose most of the bark in the burrs, but it's worth a shot.
2) I'm not sure it matters what/if anything you add to the water. Maybe others can chime in. I added soap, it smelled awful and I'm not sure it did anything.
3) I know for a fact, just from my knowledge of cooking, that you definitely want to keep the water at a gentle simmer at most, definitely below 200 degrees. Boiling water is definitely going to break down the fragile bones more easily.
3) I simmered for probably an hour, picked, simmered some more, etc, etc until it was clean. It probably took 2-3 hours total.
4) Have a good pair of long forceps to get as much of the nasal cavity picked out as you can. I did some pressure washing up in there too, and it didn't seem to help real tremendously. I was more successful just picking and scraping with a variety of tools. I did not preserve the spiral looking nasal bones, I just yanked those out. The brain, what worked for me was making a tool out of a wire coat hanger.
5) With the boil method, without whitening it's going to look splotchy, not in my mind very natural. I just used 2-3 painted coats of the peroxide whitener until it got to a shade of white that looked more natural, but not bright white.
This was picked clean, before whitening
Whitened. This isn't very good lighting, it looks more natural in person than it does in this photo. I also left the teeth natural color because I think it makes for a neat looking contrast with the white skull.
It's now a year in and I have some light greasing on the nasal passage, but really not enough to bother me. You definitely need to do a degreasing step (ammonia I think?) if that's something that will.