1)
What will cause Yisrael to become insane?
1.
Targum Yonasan: The punishments will cause you to become insane.
2)
Why does the Torah insert the (otherwise superfluous) words ""mi'Mar'eh Einecha asher Tir'eh"?
1.
Oznayim la'Torah: Because under normal circumstances, a person can close his eyes and avoid seeing what he does not want to see; but here, the Torah is telling us, the circumstances will force one to see horrific sights that drive him insane.