1)
What is the grammatical form of "Zadon"?
1.
Radak: It is To'ar (kind of person - however, here it refers to Hashem), like "Zed Yahir" (Mishlei 21:24).
2)
What are "Yomecha" and "Es Pekadticha"?
1.
Malbim: This addresses the king. Yomecha is the day that, according to the Ma'arachah, the sun of your success set (your fall was destined to begin). Es Pekadticha is [when it is proper that you fall] due to Hashgachah, based on your sins.
