Does ptsd help the mind recover after combat?

Not really. Ptsd is a reaction to an overwhelming situation which involves danger. Symptoms include avoidance, increased arousal, and re-experiencing. Effective treatment may include structured recall and discussion of the trauma to facilitate recovery from the trauma. So, while ptsd does not facilitate recovery from trauma, treatment does.
Maybe. Dependent on working issues out in counseling that are creating distress.
Fight or Flight. No, but many of the responses that occur when one is exposed to trauma can be adaptive and helpful at the time of the event(s). These fight or flight responses are designed to keep the person alive. Unfortunately, in PTSD, these responses persist in situations that are no longer threatening. Therapy can help restore balance so that the mind/body no longer perceives danger in innocuous situations.
PTSD . PTSD also known as post traumatic stress disorder is, by definition, and illness. Therefore it can't really help the mind recover after combat. PTSD is thought of what happens to a person's mind and emotional life in general as a result of combat.Recovery is dependent on each individual patient, and whether or not they attend therapy sessions and adhere to medication needs if any.