1)
Why does it discuss Hashem's Etzah and Machshevos?
1.
Radak: This is in contrast to those of Goyim, which He annuls (verse 10).
2.
Malbim: His Etzah (the desired end), e.g. the completion of mankind until the end of generations (Bi'as ha'Mashi'ach), stands forever without change. His Machshevos, the means that lead to the end, change according to the generations - exiles, redemptions
