Again... If a Dice Pool add is not specified (as Specialization and Foci are not), then they are considered MODIFIERS... Right there in the book. 

No, that's not what it says. It says that if a modifier is unidentified then it is a dice pool modifier instead of a threshold modifier. It says nothing about extra dice, as from Edge, Foci, and Specialization, which are not identified as modifiers in their relevant entries, even though every other instance of +/- dice in the book is identified as a modifier or dice pool modifier. They opted not to use that language to describe six foci, specialization, and Edge.
The MECHANICAL rule for splitting Dice Pools is in the Combat section. The Idea for Multiple Spellcasting is in the Next Chapter. What? You want them to keep reiterating a rule in every section that could apply? Not enough Word Count available for that. 

That's not how rules work. If they want the two-firearm rule for dice pool splitting to be generic, then it should be in the Game Concepts section and not specifically tied to two firearms.
I'm going to reiterate here that you're the folks that are trying to say this stuff is RAW so you can keep it in the discussion about Magic. The fact that it isn't in the book should probably deter you slightly.