They are still working on the certificates of the past year. I think nobody has recived one yet. Better wait to see your final grade.
You didn't mentioned in your post but the final project is also mandatory in order to receive the certificate.
You can see if your pset8 was graded by accessing the gradebook with the link on the progress tab in the course page.
I can not tell for sure but i think that they can not auto-enroll you in the new course. If you are enrolled, most probably is that you enrrolled yourself by mistake.
Also noticed that the gradebook is shared for the last year course and the present one, this can create a bit of a confusion.
EDIT:
It seems, as @curiouskiwi says in the comments, that everybody registered in cs50x_2014 has been automatically auto-enrolled to cs50x_2015.