HaKatan,
1.Our mesorah goes back to Yehoshua bin Nun through the Gra, Rav Tzvi Hirsch Kalischer, the Netziv and Rav Kook.
2. #4 is a halacha (Shulchan Aruch Yoreh Deah 236:6).
3. Rambam does not pasken it in Mishna Tora so apparently he ither changed his mind or what he said to the Jews of Yemen was only an asmachta b’alma.
4. They are not pesak. They are aggadata and not halacha.
5. Anti-Zionism is heresy and denial.