I am reading the rules and I see it differently.
The correct sequence is the first one you pose:
1: spend the CP
2: resolve all of that unit’s shooting attacks (to hit, to wound, to save, calculate damage)
3: On a 4+, that unit must retreat but cannot run
4: Assign wounds and remove miniatures
The rule was designed like this, so that if you surround the unit, it cannot flee, no matter how much you kill.