As a noob here & a non-GM I'd prefer this flipped. I am of the opinion the book would sell best if the meta rules on how to build things was in a secondary source. I personally think those rules would benefit sales best by going OGL but that's a bold bold step to take. Rather, point to CC.
This book should be prefab races, spells, classes (leave words like template or package out please) etc. Want to compete with the top fantasy lines? Emulate their presentation. Emulate their grammar. Throw the basics in on how to upgrade Magic Missile but don't confuse folks with long passages on how to build it from the ground up.
Also, in fantasy most folks come to the table with either a race or class (or both) in mind. Rather than say being a dwarf costs 20 or whatever points, show how many points a dwarf has to spend on their Standard build. This is a minor thing but it helps people think race (therefore The Game) before points (System). Game, then system rather than System, then Game.