Do the Eridians have a mating officiating custom/ceremony? Can they get a divorce, or something alike? How do they breed? Do they lay eggs or give birth like mammals? How do they decide who bears the offspring?
What about conflicts? Would they have enough cultures or sub-societies to fight one another? What would their wars look like? Do they have additional weapons, or are their bodies themselves be the weapons, crashing into one another?
Wow many questions! alright lets see- Yes, they do, specifics varies a bit from place to place, eridian societies are very heavy on collectivism and their social structures resemble those of insect hives, mates/becoming mates officially is legally considered one of 2 cases: the union between not just the individuals but of their whole family-clusters (and in this case the arranged marriages between smaller family-clusters are quite common.[thanks for that hc james ortiz lol]) or the formation of a separate individual family-cluster, usually in the case of more than one mate or of larger family-clusters
note: clusters are not necessarily family units; and so marriage is not the only way to join one—you could, for example, join a cluster of professionals in your field, or join your friend's family-cluster without marrying. Think of how humans have various social circles, but on a more intense level, since clusters live and spend most of their time together.
for reproduction, here's the canon answer:
and on conflicts- Oh yeah, of course they do. For a lot of the same reason humans have conflicts, actualy. Tho enterspecies conflicts are often less violent and deliberate than interspecies conflicts, since individuals of the same species usually have a shared sense of identity that transcends individual cultures (humans have that too, but since they are a lone species in their planet and there's nothing to compare they often don't notice)
Unlike humans (who, even compared to other great apes are ridiculously bad at physical violence) most eridian combat has historically been hand-to-hand, with a variety of close range weapons or simply using their own very sturdy, very durable and very heavy bodies as weapons
Their 360-degree "vision" makes it so it's kinda hard to focus on a target at a distance, that and is hard to even hear the objects when they're on air, so long range weapons are just not reliable to them
it's worth noting that with the invention of cameras eridians were able to create a wider variety of long-range weapons, but those are more their equivalent to "high military weaponry"