It's a click-baity headline. They previously required surgical transition, which results in sterilisation. You couldn't 'just' get a vasectomy or hysterectomy to get legal recognition, you needed new genitals too.
Correct, but only if you wanted to change your legal gender. So many transgendered people in Japan have yet to do so to avoid undergoing that procedure.
CSAM involves actual real life children, the term does not include cartoon child pornography. The whole reason CSAM was coined as a term was to distinguish between the two, such that law enforcement can target their efforts where it matters.
They only outlawed cartoon child pornography a few years ago, but child sexual abuse has basically always been illegal.