Rashi: They are Egyptians, on whom you rely for help! Radak - it is proper that also they afflict you, for you abandoned Hashem. Malbim - this is unlike nature. (It is special Hashgachah.)
2)
Why is it written v'Sachpanes, and we pronounce it v'Sachpanches?
1.
Radak: It is a city in Egypt. It is called both of these; they are close to each other.
3)
What is the meaning of "Yir'ucha Kadkod"?
1.
Rashi: They will crush your skulls. Yir'ucha is an expression of crushing. The Targum of "v'Ratzutz" (Devarim 28:33) is u'R'I'a.
2.
Radak: They will break [the skull]. This is like "Ro'a Hisro'a'ah" (Yeshayah 24:19), "v'Ra'u Daliyosav" (below, 11:16), "u'R'u Es Eretz Ashur" (Michah 5:5). Striking the skull is severe, for it is in the middle of the head and divides it - "v'Taraf Zero'a Af Kadkod" (Devarim 33:20).
3.
Radak citing Targum Yonasan: They will kill your men and despoil your property.
