Most experts would agree, that the lower the RPM, the lower the wear on the engine
That may be true but I have never seen any data on it.
Keeping other things equal, MP = torque, so producing a given HP at a lower RPM means the torque (i.e. mean cylinder pressure) is higher. So, a lower RPM will produce more wear on bearings, etc. all the way to the contents of the propeller hub.
I think high cylinder pressure is an additional factor that can reduce your engine's life.
Yes; cylinder pressure = torque.