Let's see:

I don't have the five dubia in front of me, but IIRC, the answers would be that the Church will always teach that there are moral norms which may never be disobeyed; that all persons who engage in sexual relations with someone other than than the husband or wife to whom they are validly married are adulterers; that adultery is always grave matter; that all persons who are conscious of mortal sin must not receive Communion; that all persons who are publicly known to be engaging in grave sin must be denied Communion.

If the Holy Father teaches what the Church has always taught, then he is a Catholic. If the Holy Father teaches anything other than what the Church has always taught, then he is a heretic.