As someone who has had panic attacks (not on planes thank goodness), no you can't control how or when you react - my problem spot is heights and I work in a tall building. I'll go months being okay and then all of a sudden I can't handle being on the 4th floor of a building - unable to breathe, feel like I'm going to pass out, I usually get very quiet as I'm trying to focus and calm myself (doesn't always work). A friend though starts hyperventilating, then screaming, grabbing other people, and gets very demanding - she is a very quiet person normally; her reactions during panic attacks are completely different than her normal personality. Very probable this woman either had no idea she would react this way or thought she had worked through the problem (there are lots of fear of flying courses/therapy programs out there).
As to the luggage, I don't know about you but if somebody is to the point of screaming "we're all going to die" and forces her way off the plane, then I definitely DON'T want her luggage remaining onboard with me. For an international flight, it would be required to remove her luggage, for a domestic flight it would be the smart thing to do as well.