Did JPII actually write the Catechism or did he merely give it his Imprimatur? Also, are you saying that this document consists completely of ex cathedra declarations so everything it says is infallible?
No St. JPII Didn't write the CCC, it was edited by Christoph Cardinal Schönborn who has since turned into a complete loon. It has turned out to be an awful tool for catechesis (the purpose of a catechism I would think) evidenced by the fact that most of the world that has been heavily exposed to it has lost the faith. We've had it for 20 (very) odd years and rather than being the foundation of a "new springtime" it has helped to usher in Catholicism's nuclear winter.
That's not to say it's totally worthless, necessarily. There are some profoundly beautiful passages in it, but it suffers from the same problem of the documents of Vatican II: it reads like it was written by a UN committee.
No re ex Cathedra. There are levels of certainty in Catholic teaching. Refer you to Ludwig Ott book.
The Catechism orderd and approved by JPII and there were a couple of fine tunes. Dogma DEVELOPS without contradicting so more to come.