For bunnies just carefully cut the abdomen from the anus to the throat and just simply pull out the heart, liver, stomach and intestines. I skin them by cutting a slit in the back and basically pulling the skin off and cutting the head and feet off. To quarter them cut the front legs and shoulders off, and the back legs and thighs off so you wind up with two front quarters, two hind quarters, and the torso.
For squirrls I'd advise going online and Google skinning squirrels to view the different methods of skinning (there are a few). I usually don't field dress them until after skinning. Quarter them like a rabbit. The hide is tougher than a rabbit and a technique is involded in skinning and is best watched than read.