Jon,
Like most of these guys have recomended, I use peroxide from the beauty salon. They also sell a develper solution to mix with the peroxide that can make the process go faster. Also as mentioned, don't get it on your skin or you will get a chemical burn.
I degrease by slowly boiling the skull with a about half a handfull of Electrasol automatic dishwashing powder (as mentioned above). If you keep it at a medium rolling boil, put a couple of handfulls of sand in the pot. It not only helps scrub off the skull, but scrubs the pot as well, making clean up easier.
Also as mentioned before, I use my fish fryer burner and a big pot that is used to fry turkeys in to boil my skulls. Since I do several dozen skulls a year (of various types) I have dedicated the pot to this purpose.
Hope this helps. These guys have given some good advice.
OkKeith