Okay, forget what I posted about concepts and all that. Main questions are nice and bold.
Now for the question I still have. Namely, why are mortals so special? Because they can reach CHIM? If so, what do they have that other entities do not have? Is it choice?
Wild Speculation Alert!!!---If mortals are the ability to choose (and, by CHIM's associations, the will of everything), then that may explain the waxing and waning power of a concept according to the attention paid to it by the masses (we, the everything, approve of your existence), as well as divine intervention (we, the everything, say to do this). Because of this (and the conflicts between various mortal factions), it would seem that the world of mortals has it's own, unthinking to-do list.
Also, could it be that Lorkhan is do what you want (freedom in creation), and Akatosh is do things this way (cycle, cycle, fix it, fix it)?
Or maybe all concepts can move and do, and the mortals simply have more ideas to use (as they are made of all that came before).