i may not get time to do the writeup but i will post it if i do.
the caq is a weird entity. it's certainly a conservative party, but it had an unusual support for secularism. secularism is generally more of a liberal idea, and religious ideologies are generally considered to be more in the realm of conservative value systems. the fact that this was all mixed up in quebec was an idiosyncrasy of quebec politics and a result of the absence of a real spectrum for several generations due to the sovereignty question stagnating the local political spectrum.
christine frechette strikes me as more of a traditional conservative than legault and as such i'm skeptical of her ideological support for secularism. in the quebec spectrum, that aligns her more with the liberals (who are conservatives in quebec).
if you want to ensure quebec continues forwards towards secularism and isn't driven backwards into some mushy concept of multiculturalism, i would vote for the pq instead.