1)
Why does it say "v'Nasati Eschem b'Yad Zarim"?
1.
Malbim: Do not think that I will remove you from [the city], and you will flee to where you want. In truth, they left at night in order to flee. Hashem gave them into the hand of Zarim ? "va'Yasigu Es Tzidkiyah b'Arvos Yericho" (Yirmeyah 52:8).
2)
Do we find "v'Asisi Vachem Shefatim"?
1.
Malbim: Yes (via Melech Bavel) ? "va'Ydaber Ito Mishpatim" (Yirmeyah 52:9).