3: I'm not so sure on that one, I'd have to doublecheck every weapon with one to check first. I'd suspect internal actually.
I thought internal too. But looking through the entire list of firearms, there 11 firearms that include a smartgun systems. Only two of which are specifically named internal. So either the designers made accidental omissions on 80% of the smartgun firearms or, more realistically, the only smartgun systems that are internal are those that specifically mention it... at least until an errata or FAQ states otherwise.
4. I... guess so? Not really something I put any thought into.
It comes up during chargen and buying weapons off the blackmarket. For example if a weapon comes with an internal smartgun system, and I wanted to throw a vision magnification enhancement on the smartgun's capacity 1 camera then the +2 availability rating might push it over the 12max, so specifying where that +2 can make a noticeable difference when building a character and later in the game when trying to find gear.
7. You definitely need an action for that - not sure if it's a Ready Weapon action, though.
That's what I said. A full simple seems excessive for just the folding stock. Or at the very lest seems like a good candidate for a wireless type free action.
Additionally, the wording on the Yamaha Raiden, Ares Antioch-2, and Panther XXL need clarification. The Raiden's smartgun system may or may not be integral, the Anticoh-2 lists a smartlink instead of a smartgun (probably typos), and the Panther just says a built-in smartgun without specifying whether that means internal or integral.