Milhouse,
1. I wrote that there is an opinion that red strings are darchei Emori not mezuzah.
2. If you are shogeg then maybe you get an “E’ for effort. On the other hand, you are lacking the full merit of the mitzva (that is also a protection). In any case, we do not know how these things work. It may be that someone was protected in this world but loses what he would have received for the merit in the next.
3. My interpretation of Rebbe’s intentions is at least as good as yours.
4. You are simply not correct that Am Yisrael has accepted the Zohar and Arizal’s pesakim. Rav Ovadia, for example, generally opposed paskening according to them where they contradicted the Mechaber. Ashkenazi poskim very rarely even mention them. The <a href=”http://www.hebrewbooks.org/pdfpager.aspx?req=14520&pgnum=23
“>Tzitz Eliezer has a long teshuva on this topic. Rav Yaakov Emden and the Chatam Sofer believed that Rashbi did not write most of the Zohar. See “Rabbi Berel Wein – How Authentic is the Zohar?” online.
Laskern, there is a big debate about the place of Kabbal in Halacha. The Gra says that there is no machloket between the Gemara and the Halacha except one – whether or not a person may walk past someone who is davening on the side (the Gemara is meikal but the Zohar is machmir). However, this sometimes requires interpretation. For example, the Zohar says very harsh things about people who shave. Rav Chaim of Volozhin says that that only refers to someone who uses a razor.