After the Germans were expelled from the city, what was it like for Poles who were resettled/living in Wroclaw in the 1950s and 1960s? What kind of challenges did the Polish government and urban engineers face taking over one Europe’s largest city?

I'm not quite able to give you a full answer, but you might be interested in Gregor Thum's book Uprooted: How Breslau Became Wrocław during the Century of Expulsions (trans. Tom Lampert and Allison Brown, Princeton University Press, 2011). It comes highly recommended to me by a Polish historian friend, who happens to be from the Wroclaw area, and it got very good reviews in multiple different English-language journals upon its translation, so you don't have to take just my word for it.