There is no real guideline for appaloosas. There are so many factors involved it would make your head spin. You would need to know the stallion as well. In the end it would be a crap shoot as to what color.
In appaloosas, as with anything, if you are looking for a specific color/pattern you will be better off buying a horse already on the ground rather then attempting to breed to get it.
Some people think fewspot means the appy only has a couple of spot. Fewspot means that the horse inherited the LP gene from both parents. A fewspot requires TWO appy parents with the LP gene. They will always be white in appearance sometimes with color on legs, ears, and in the girth and flank area. There is also the snowcap in which the white is mainly restricted to the back and hindquarters but its too much detail for me to go into right now.
My girl started out with a bit more color on her neck and head and has whitened up quite a bit. Fewspots will always guarentee you an LP gene on any future foals but are known to have vision problems, not all of them. My girl doesn't have the best night vision but is otherwise perfectly fine.