It's all digital from start to finish, in Photoshop. I do paint (I haven't in a while though), but for commercial work it's just more practical for me to keep it digital.
The process is pretty close to the traditional methods. A very rough sketch stage in PS. A pencil stage in PS and then colors. The way I approach the coloring stage varies, sometimes I do flats, and sometimes I just start painting. I tend to do flats when I have a less clear picture of where I want the colors to go, or if I plan on dropping gradients over certain elements. In the case of Buffy #4, I laid down rough colors under then line art and then did the finishing colors on top of the line art, so that the lines disappear and the picture takes on a more traditionally painted look.
I hope that filled you in some, if you have specific questions feel free to ask.
Thanks very much! I saw great Escher book at the books store that explained how he made his complicated patterns. The book was full of his sketches, which showed how he worked the patterns out...the book binding fell apart, in the store, while I was looking at it though lol.