Yes, Ziminski shot a pistol into the air. Is charged with arson (but, oddly, not with shooting that gun) and was not called to the stand, there was a fight over that in closing arguments (both for defense, then for prosecution, then going to the judge to settle the dispute).

Rosenbaum is the one that threatened Kyle previously. It's not clear how they're related, but Rosenbaum and Ziminski were together in photos where a lot of the stuff was going down, this was referenced by the defense a lot in their closing arguments.