When built properly, roads are quite resistant to the elements, though the execution is often culture-dependent. Roads for light loads can be built much cheaper.

Snow plowing absolutely destroys roads. The blade catches on the smallest imperfections and creates potholes. Then water gets in and the freeze/thaw expansion cycle quickly makes things worse. Here in Canada roads really don't last very long before they have to be peeled up and put down again.

Yes, but this doesn't create particle pollution, just potholes.