What is the significance of foreigners building your walls?
Radak: Aside from gifts that they will bring to you, they will serve you in your land and do your work.
How will kings serve you?
Radak: They themselves will serve you, and all the more so the nation will!
Malbim: They will supply gold and silver to help the workers build.
Why does it mention striking you in His anger?
Radak: Then you will realize that all your matters, for good and for bad, were from Me. Nothing is chance. When I was angry at you, you were a slave of slaves in Galus. When I am pleased with you - refer to 60:10:2:1.
Malbim: I did not strike you with Chemah (inner anger); one who does so waits until the measure [for punishment] is filled. Rather, I struck you amidst Ketzef (light anger).
What is "uvi'Rtzoni"?
Rashi: When I was reconciled.
How did Hashem show mercy?
Malbim: He appeased [Yisrael] for the past - "Odecha Hashem Ki Anafta Vi" (12:1).