Hi,
I just found your review questions. Thank you. Am troubled by the answer to Q1. The earliest zman is not tzais. It is bain hashmoshos.. See the discussion on Amud Bais..
Dovid Gelb, Brooklyn, NY
The Gemara at the end of the page specifically mentions Tzeis. What makes you think otherwise?
The Sugya on Amud Beis cites many opinions. That of Rebbi Yehoshua cited there conforms with our Mishnah which holds Tzeis.
Wishing you a Kesivah va'Chasimah Tovah,
Eliezer Chrysler