How is it possible that their garments did not wear out during their entire stay in the desert?
Rashi (citing a Midrash) and Ramban #1: Because the Ananei Kavod washed and ironed them even whilst they were wearing them. Moreover, the children's clothes grew with them, just like a snail's shell grows with it.
Ramban (citing the Ibn Ezra): The Manna did not create perspiration that causes clothes to wear out. 1
See Ramban's objection to this explanation.
Why did their feet not swell in the way of people who walk barefoot in the desert?