1)
Why did Hashem consent to the Satan?
1.
Malbim: It was in order to test Iyov. It was not due to prior sin - the verse testified that he was clean! His friends erred about this, until the last, Elihu, revealed this at the end.
2)
Why does it say "va'Yetzei ha'Satan me'Im Pnei Hashem"?
1.
Malbim: Lack and loss do not come from Hashem - He makes things exist! Rather, they come from Hashem not making existence - Hashem's power left the place. This enables lack, like I explained "Yotzer Ohr u'Vorei Choshech."
