Matt Calling and George Katting were Calaway's partners. George was killed in a fire fight eight years before Calaway joined the ISS Descent crew. Calling tried turning Calaway into the authorities on Setlik III after Calaway robbed a deposit of Alliance credits. Calaway caught wind of this and shot him in the head. Calling survived the shooting but was confined to a bed for the rest of his life.
The shuttle's standard weapon complement was 2 forward type-10 phaser arrays and 1 aft type-10 phaser array, and 2 forward and 1 aft torpedo tube with 15 photon torpedoes. Over time Calaway made several improvements. (Star Trek: Shattered Universe)