Zorg Empire

I know battles take 6 rounds to complete, but how many times does a fleet/defense fire each round?

If a ship fires at a defence/ship and destroys it with excess attack strength, does the excess attack strength go to damage other units? Eg, A Death Star fires 200 000 attack points at a light laser of 1000 hit points. Does the excess 190 000 attack strength go on to damage other defences or units?

I'd like to know how the damage is distributed throughout the defense/fleet. Since it doesn't seem to target a specific group first.