This is just a logical deduction of what an elf that is immortal will be.
1) Elf may live longer than anything else but their perception of time in most case is the same as human. Which means a minute is a minute to them. A creature that have slower perceptions of time is something else (for example the sloth “Flash” in zootopia). The perception of time of a creature depends heavily, not on their lifespan, but the speed they require to adapt to their environment. If you need to move as fast as a human to hunt or gather the food as similar to what human eat, your perception of time will be more or less similar to human to the point of indistinguishable.
The elves could develop a way to slow down their perception of time as a coping mechanism for their long life if they have absolutely no reason to perceive time any faster. This would mean they have long duration within their lifespan that is consisted of uneventful period. This can only happen if the elves doesn’t have danger to their life (these dangers included hunger, thirst, disease, predators, enemies, competitors, habitat destruction… and a lot of other non-life-threatening thing like loved ones etc.) If you have elves that have truly slow perception of time for all of their life, the elves would evolve into a sloth where they slow thing down to save energy.
These deductions would be wrong if the author said “no, my elves perceive time like that because I create them like that”.
2) The establishment of a government would only arise when there are activities that require large group of elves. If the elves can be sufficient by themselves, they will have no incentive to create a government. This, however, applies to every single race. If a human or an orc can be self-sufficient without help of other human or orc, no kind of government would exist. At most, they would only need a place of gathering and that’s it.
In case the elf truly requires a government, that means there are imminent threats to their livelihood (climate change, food shortage, disease, contaminated water, enemies etc) that requires a government to deal with those on a daily basis to achieve a solution. In that case, their government would move quickly, and their meeting and discussion would be not much different from human’s.
If it’s something like a 50-50 chance of a large flood coming every 10000 years, the elves wouldn’t make a government for that. At most they will only have a place that all the elves would gather to assess the situation before the flood and see how to deal with it.
3) The knowledge subject is also problematic. Unless you give the elves a cheat skill like Infinite data storage, their knowledge would be less than a civilization. All manner of creatures if they are truly biological would only have a finite memory. Unless you invented something in the mind/soul/ whatever abstract effect to deal with memory, there is no way they can remember the knowledge of a civilization. Even with photographic memory they would not be able to remember everything they have learned. Their mind just doesn’t have infinite storage. The ability to learn and recall an information (photographic memory) has no connection with how much they can remember (data storage).
That, however, is just a part of the equation. Remember that you have mind and body. Your mind can recall the knowledge to create atomic bomb but that doesn’t mean your body has the skill to do so. More importantly, your body would lose their skill overtime just as your mind forget memory. In order to not losing their crafting skills, they would need constant practice and just remember that there are countless skills (lab skill, glass blowing skill, carpentry, horse riding, surgery skill, martial art…). Even if you spend 10 mins for each skill, by the time you return to practice the first skill your body would have already forgot or having the reflex for that skill overwriten by the other skills you were practicing. This is again the issue of limited data storage space. Your muscle memory and your brain memory are not infinite under these settings.
Of course, if you as the author said that “my elves can’t get memory loss” then what you assumed would be correct.
4) It’s not possible to say that elves will not develop kinship. The only exception is if the author (the god of their novel) says that “my elf can’t develop kinship”. Other than that, under normal circumstances elves would develop kinship with individual within their species or other species. If you agree that they can live forever unless someone kills them, then you would agree they have a heck of a long time to live. Thing that live will change be it their body or their personalities. Some will develop attachments. Then after losing too many friends, they will be driven to suicide or show a disdain to life or having withdrawal effect and become hermit hiding from the world completely.