The Skybreaker radiant kind of sounded like he was pitching a protection racket. I guess that works within his legal framework?
I can't wrap my mind around shardbullets. Gotta be some kind of mix of investiture to make that work. The only bullet like force on roshar seems to be a reverse lashing, but only the windrunners can do that. I don't think it can be a shardplate spren, it just seems from the scene that the gun is made out of the same material as a classic shardblade. Assuming it's a singer though, we really have no idea how surges will effect them in combination with their already existing forms, so it's really up in the air.