Most non-chassidic ashkenazi Jews follow the Mishna Brura. Mishna Brura rules that Zohar is not to be followed if it contradicts, standard halachic texts and the poskim.
Mishna Brura does however, (unlike Chatam Sofer) give the Zohar a tie breaking role, if there is an argument among the standard halachic sources.
This is to say, the Dor Daim speaker goes too far in his attack on the beliefs of other Jews. One does not have to be a Rambamist, to have halacha supersede zohar views.
Chatam Sofer and in our times, Rabbi Dovid Bar Chaim have almost entirely taken out zohar from halacha considerations and they are not Rambamists.
point 2, Even if the vast majority of the Zohar was written at a much later date, nevertheless it is still many centuries old and will at times provide useful new outlooks and commentaries. We don't have to "throw the baby out with the bathwater." We just have to be somewhat more skeptical.
To be honest though after having been convinced about the late authorship of many parts of the Zohar, I personally try to minimize my connection and contact with the book. But I don't look down upon others, who are more "into the Zohar" as long as they aren't violating halacha.
point 3, Rabbi Saadia Gaon indeed, does reject the idea of reincarnation. But Ramban, writing one generation before the Zohar interprets the Biblical book of Iyov {Job} 33:30 as well as Breishit Genesis 38:8, as supports for reincarnation. This seems to me, an optional belief in Judaism, where you are free to accept or reject. It is not a fundamental element one way or another of Judaism.
