1)
What is the meaning of "Asher la'Melech Nish'an Al Yado"?
1.
Radak: The verse is abbreviated. It is as if it says 'ha'Shelish Asher la'Melech she'Hayah Nish'an Al Yado.'
2)
Why did he mention windows in Shamayim?
1.
Radak #1: Rain will fall from them.
2.
Radak #2: They are for wheat and barley to fall, like manna fell. Yonason translates, if Hashem would open windows and much food from Shamayim
3)
Why does "Hinchah" end with Chaf Hei (and not with final Chaf)?
1.
Radak: We find like this - "ha'Nitzeves Imechah" (Shmuel I, 1:26) and similar verses.