When is "Mikeitz Sheva Shanim" referring to?
Rashi: It is referring to the first year of the Sh'mitah (the eighth year of the cycle). 1
Targum Yonasan, Moshav Zekenim and Hadar Zekenim: It to the year at the end of the Sh'mitah cycle - to the beginning of the year in which it is forbidden to plow and seed. 2
Rashi: Which is still called 'Sh'mitah' because the Dinim of Sh'mitah still apply. Refer to 31:11:0.1:2.
The Mishnah in Sotah 7:8 states that it is in the eighth year! Perhaps it explains the simple meaning, differently than the Yerushalmi. In our text of the Yerushalmi (Yom Tov Acharon), 'ba'Shemini' could mean the eighth day. However, it says 'be'Motza'ei Shevi'is', and also in Avodah Zarah 1 (PF).
Why is Hakhel read specifically in that year?
Hadar Zekenim: Refer to 30:10:1:2. Since, as opposed to other years, everyone rests from working the land the entire year, and are available to follow-up on what they hear during Hakhel.
What are the implications of the word "be'Mo'ed"?
Sotah, 41a: It implies on a Yom-Tov - at the beginning of Chag ha'Succos 1 of the eighth year.
Why does the Torah need to give so many signs as to the date of Hakhel - "mi'Keitz Sheva Shanim", "Sh'mitah", "be'Mo'ed", "be'Chag ha'Succos" and "be'Vo Kol Yisrael"?
Sotah, 41a: The Torah writes "Sh'mitah" to teach us that we only count seven years once the Sh'mitah cycle has begun 1 and the eighth year is the Sh'mitah. And not immediately; "be'Mo'ed" - to teach us that Hakhel takes place, not at the end of Sh'mitah, but at the beginning; "be'Chag ha'Succos" - to teach us that it takes place, not on Rosh Hashanah, but on Succos;, and "be'Vo Kol Yisrael" - to teach us that it takes place at the beginning of Succos (on the first day of Chol ha'Mo'ed) 2 and not at the end.
