All excellent points and ideas to concider when trying to put together a
relatively realistic elven society. If I may be so bold as to add some thoughts/ideas/questions to your points:
1) Would being an "eternal teenager" mean they are progressive or concervative? The way you word it makes it seems as though humans get progressive as they get older, but that is not
usually the case. There's some quote about being born a democrat and growing up into a republican........
2) This one, I feel would have to have been dealt with for the race to survive and still be a community, instead of a bunch of very small groups - or even killed off (by themselves). Something like term limits would probably have been instituted, say 100 years or so. When your term is up, you step down and the next (chosen, voted, in-line, whatever) leader is instituted. Maybe a challenge system - though I doubt it would be anything combat related unless they are a particualrly violent elven tribe.
3) Exactly. When you have proof of the soul and life after death,
everyone changes how they deal with dying - not just elves. That, right there, would necessitate a change in the basic cultures of every species on (or in) that world.
4) Long term planning would be very typical of elven society. So long term that many of the other races would think they don't have any plan(s) at all. In this situation, selfishness (which is what I believe lies behind the vast majority of our problems: economy, ecology, etc...) actually helps in making - or maybe more appropriately: keeping - the world and society "better" places. (I put society in quotes because, as we all know, one person's idea of good/better is not necessarily anothers.)
5) The big difference here is that these would be "pets" that you could form real....REAL...relations with. (Please, no cracks about animal
lovers, it creeps me out
) That throws a bit of a monkey wrench in the whole business. But would be a great explanation as to why the elves hold themselves apart from the other races. They have learned the hard way that feeling that loss, repeatedly, is nothing to seek out. Maybe some of them go further and victimize the other races to force themselves to think about them differently - less somehow. A defense mechanism of some kind. Or maybe why some human (or other race's) families are watched over by an elf - they are decendants of his/hers.