We didn't know what we were was unusual for autistics until quite recently! We knew some autistic people had worlds in their heads and assumed that also meant a detailed paracosm and inner life with people you couldn't get rid of in your head... then we became close friends with a lovely person with DID and had the '...wait... that's a Thing‽' realisation.
"What happened to you?" Soo much child abuse. Don't ask other people that.
"How many of you are there?" We have absolutely zero idea, and also it's complicated.
"Do you have DID?" Nope, but seem to fit the OSDD criteria.
"What's your opinion on syscourse?" The DSM-V isn't going to suck you off, bro. I've had plenty of diagnoses 'changed' out from under me as psychiatrists redefined conditions but my experiences remained the same.