That's a lot of stuff to take in to be sure, but what I want to address is the idea that alters 'kick you out of your body'.
In dissociative identity disorder, there is only one person... there is no other being there who can kick 'you' out of your body and take it over. The cause of the identity confusion, amnesia and black outs is a lack of association of the personality. It is caused by sufficient trauma and / or emotional neglect in early childhood which prevents the normal developmental integration of the personality from happening. In other words... there are no other beings from outside that have come in and taken you over... the identity states present in DID are all normal aspects of one person... they just never had the opportunity to learn how to integrate into one identity state or work as a team, so to speak.
I want to say though that I completely understand how alters feel like they are foreign and not of the self, especially in the early stages of therapy. But I still want to stress to you that alter states in people with DID are NOT from anything that originates outside the self.