What is the meaning of "Lu"?
Rashi: If. Radak ? this is like "Lu Hachayisem Osam" (Shoftim 8:19).
Why does it say "Lu Chayah Ra'ah A'avir"?
Malbim: It is lighter than hunger, and comes beforehand. One might have thought that for this, their merit helps to save others.
What is the grammatical form of "v'Shikalta"?
Radak: It is Po'el Yotzei (it acts on others). The land does not bereave them ? it is like a mother to its residents! The Chayah bereaves the land.
Why is "Shemamah mi'Beli Over" said only regarding Chayah?
Radak: Hunger, sword and plague make the land desolate, but people pass through. However, when it is desolate because Hashem sent Chayos ? "v'Hishlachti Vachem Es Chayas ha'Sadeh" (Vayikra 26:22), people fear to pass through.