My guess is a law clerk leaked it after being instructed by a Supreme Court Justice. I think either Sotomayor or Kagan.
My bet is on Sotomayor. Kagan’s politics and view of the law are reprehensible in my opinion, but she does have an understanding of the rule of law. Sotomayor has not demonstrated that she has any such fundamental principles.
Yes. Not all the staff submitted to interviews, so my suspicion would be that those who did not are involved, with suspicion falling then on the particular Justice they worked for. And that seems most likely to be Sotomayor.