1)
Why does it mention Ketanim and Gedolim only regarding Yir'ei Hashem?
1.
Radak: "Beis" includes small and big 1 , so it was not needed for Beis Yisrael and Beis Aharon.
2.
Malbim: The great Brachah that Hashem puts on the Gedolim (Yir'ei Hashem) takes effect also on the Ketanim (Beis Yisrael), like I explained about "Ki Etzak Mayim Al Tzamei" (Yeshayah 44:3).
1
Radak here and in verse 14 implies that this refers to adults and minors. Malbim holds that it refers to people at high and low levels. (PF)
