Harder surfaces are actually easier to run on than dirt trails. You get much more of the energy you put down with each footfall back. This is important because your foot is basically a spring and designed to recover some of the energy put into making each step.

Harder surfaces are a mixed bag. Yes you run faster but your feet, ankles and knees take more impact and damage.

Not if you strike with your forefoot. If you are landing on your heels, then yes. Don’t do that.

Human bipedalism evolved in places like the East African Rift Valley which is rocky, hard packed ground and not at all the soft grasses people imagine. If you've ever hiked in Pennsylvania, it's a bit like that.