Well, let me clarify: the City Elves aren't kept in the cities, as such - for suppression of their Immortality or any other specified reason. However, they are expected to live amongst, and not apart from, humans and to embrace the Chanty's teachings the same as everyone else. It was living apart, in the Dales and trying to reconnect with their own culture and gods that brought the wrath of the Chantry down upon them with the Exalted March of the Dales and since then they have not been granted any lands to call their own or permitted to create any all-Elf settlements. The Dalish defy this and so they are harassed and have no real protection under the law from that harassment. Free / cheap labor (depending on the state of servitude or slavery) is the economic reason to keep the Elves in cities and oppress them with second class citizenship and curtailed rights. They have no representation in any government and aren't allowed to institute their own either.
It could be stress, poor living conditions, bad diet, overwork, high violent crime rates of the ghetto etc. that cause the life span discrepancy - The wild and living as subsistence hunter gatherers isn't an easy lifestyle either, mind. I get the impression that's not the case, as the First in question says we are talking about double to triple life-span or better in that bit of dialog. Ten - fifteen years, sure maybe conditions - double or triple is something else I think.
Elves in DA certainly do not have a superiority complex - even the Dalish are not really on a superiority kick so much as they are bitter and disgusted about the plight of their people being ignored, both by the humans and the elves who have accepted the yoke of city living. They seem peaceful about the idea of preserving as much as can be preserved until the eventual day when Elves are given a fair shake again and can revitalize their culture. When they got the Dales they didn't start the conflict with the Chantry, they just didn't want to worship Andraste and her Maker because they believed she as a great lady who had helped them, but not a god and not one of their gods. Again, the First covers this - they honor Andraste for helping them be free from slavery under the majority of the Tevinter, but they don't actually worship her or her Maker. Merrill goes into it some too - she says the Chant is pretty but she doesn't need to borrow another story to explain the world, her people already have one.
TES Elves - some are very haughty some are not. Technically I believe all Mer (non Men) are a strain of Elves from antiquity that diverged according to Mythic forces (gods, deadra, etc.) interacting with and still tinkering on the world. I'm not 110% sure on that one though - we need a TES lore expert; I'm much more up on my DA lore than my TES lore although I am not sure I'd say expert in either because I don't engage in the extra-game materials like the novels the comics and so on, which sometimes become additions to the canon and sometimes operate semi-independently. I stick to what's in the games as much as possible, with some supplemental knowledge from having been a denizen of the Bioware DA boards for some years and reading author/producer comments there.
