I didn't say that the quest will be easy, nor the results permanent. It's all RP, so it's up to you to make it as realistically difficult as you think is right :]
As for the racial differences, indeed they are there. Structure, habitat, diet, and other factors all play into the equation. I cannot see Dermorians living as long as Enkidukai, as our predisposed expectations of elf longevity interfere. But I don't see this as a big deal either. It makes for colorful characters and a colorful world. It's not a limit any more than Dermorians not having a tail is a handicap.