As far as I know the weapon information inside the game is derived, yes. I could be wrong, mind you, but it seems to me like we're actually viewing mechanical data (ie spread 2.1 used instead of just saying "short range" or some crap). Characters are randomly generated so this is definitely derived (especially since one of the devs explained how it worked a while back or some such)
Damage however will always show the damage dealt by the selected fire mode, not by a single shot (this makes sense and is preferable, personally).
I'm not sure the up-to-date info is stored anywhere except in the game itself, really. Depends. I think one of the devs wrote something about how all the different statistics work; the most up to date WEAPON information is located in that game.
Although I'm not sure if that's outdated or implemented or what.