: There is also the strange paradox of the events of the Silmarillion, which Tolkien wanted to present as a sort of invented mythology. This is how they are presented in LOTR, as events of a mythical past. Though to some of the characters of LOTR such as Galadriel, Celeborn, Cirdan etc these events were those of their own memories and therefore most definitely non-mythical. Tolkien would have been better advised to have made his elves long-lived compared to humans but certainly not immortal.

I disagree, first of all elves are not truely imortal, any more than men are. They are subject to death, just not by age, until the world itself ends. In that sense its only that humans have an extra way to die.
Secondly the mythical events you refer to in LOTR were only mythical to some. To Aragorn the lay of Luthien and Beren was no more mythical than an event of our history is to us. The events of the last alliance certainly were not mythical to elrond, as he told frodo.. he was present as Gil Galad's standard bearer... what tolkien did with these "mythical tales" was briliantly set up a scenario (much like our own world) were the events of the past are quickly forgoten by the masses and relegated to mythology while truely remembered by only a few. A perfect example of this is in the Hobbit, Smaug had been sleeping in the lonely mountain so long that many of the young people of Lake town didn't believe he really existed even though there were old folk among them who had actually seen him.
As for differing motivations I think that Tolkien did a great job of showing how the elves motivations did differ from humans... early on in the first age they were much the same but that was because the elves were new to the world and had not experienced much of it such as building their own kingdoms etc etc.. but even then the emphasis of the elves was much more on excelling at their craft and art whereas humans were concerned with eating sleeping reproducing and surviving. But certainly in the third age the difference of motivations is even more appearent, for the most part the elves are just trying to maintain a fading world, a people of twighlight who have outlived most of the world that they loved and now are faced with the last task of defeating the dark enemy and finaly loosing their world. whereas men are for the most part concerned with moving on ward and upward in the third age, carrying on business and life.