User blog comment:Darkcloud1111/Good Idea, Bad Idea~Painting the Town.../@comment-6830001-20140817110008/@comment-2006510-20140817170438

No impact on the current story; but it is to slowly build up his character, which is also important (and not just by itself; likely to help with future stuff)

And as far as 'special' being vague, YMMV; I thought it was pretty clear that Ruby was talking about Yang's Semblance (so obviously releasing fire is just an aspect of it, unique to Yang; if anyone else had this Semblance, it'd probably show up differently). Plus not being fully-explained isn't a bad thing, but that's just me

As for the Dust shopkeeper, he's suffered his wallet being stolen and his truck being crushed a bit in addition to being robbed - he's probably trying to get extra money. Plus henchmen commonly don't have all the info from above (especially littler details)