1)
Why does it say "Yishlach Devaro"?
1.
Radak: Doctors heal via actions. Hashem's cure is different; His word alone heals. His word is His desire.
2)
What is the meaning of "va'Yimalet mi'Shechisosam"?
1.
Radak: He will save their souls from destruction that was close - "they reached the gates of death" (verse 18). This is like Elihu said "va'Tikrav la'Shachas Nafsho" (Iyov 33:22). The singular of Shechisosam is Shechisah. The suffix Mem hints that they caused this via their sins.
