Summoning Do's and Don'ts; or, What's Up with Carbuncle?

Much is made during the story about the dangers of summoning primals. I don't think it's a spoiler at this point, after 1.0's story, to mention that Louisoix was hesitant to perform the summoning of the Twelve and held it off as a last resort. Given that summoning siphons a large amount of precious aether in order to sustain a primal's presence in our realm, and that's a bad thing, I have two questions.

1. What is sustaining Carbuncle? More to the point, what is sustaining the hundreds and hundreds of Carbuncles running around? Why is summoning it not forbidden? I understand that probably it is not a true primal, but it is an aetheric being, right?

2. Why on Hydaelyn would Free Companies be allowed to summon primals at all? Not to bring down all those SMN who are really looking forward to pulling a lion out of their hats for once, rather than egi bunnies, but if it's bad for the beastmen to do it, why would it be cool for adventurers to do the same?

For the matter on Carbuncle I'm not actually viewing it as a 'traditional' summon. I'm picturing it more like a spell given form more than anything else. Is this true? probably not but its how I'm viewing it for now.

As I understand it, Carbuncle is Arcanima (Arcanist Arts) given life.
The carefully calculated stratagems of the Arcanist order, given form to act out these stratagems under the command of the one who did the calculations in the first place.
Of course, with how the Nymian Scholarly arts seems to be the root of Arcanima as we know it, Carbuncle might actually be a creature similar to the fairies Eos and Selene, although due to how common the knowledge of Carbuncle's "summoning" is, it might not be collected enough to sustain a personality, like with the fairies.

The Egis being mere shards of a Primal's essence, seem to require little more than what Aether a single person can produce. While it is likely to be far more straining than most high-level Black Magic/Thaumaturgic spells, it is more than likely fuelled the same, by tapping your inner aether reserves, instead of sucking the aether out of the atmosphere.

For what I understand, the summoning of the Primals costs aether, and to sustain it costs aether, and when a primal is 'defeated', all that aether is released again and returned to Hydaelin.

That means that to summon Carbuncle, you borrow a bit of aether, and return it when you release Carbuncle... the Primals, however, do not plan to return anywhere, anytime soon. They'd rather absorb all aether and own the world.

Yeah, the Primals only consume more and more to grow stronger. Carbuncles are recyclable, since we dissolve them when not needed. :)

Carbuncles are environmentally-friendly. :p

I believe the ACN story explains Carbuncle (to a degree) when we are told that we use a small crystal as a catalyst to summon him. How we get that crystal, I haven't a clue... And obviously as Carbuncle isn't a primal he isn't going to take that much aether to summon or sustain.

Didn't the leader of the arcanist's guild say that carbuncle is some sort of manifestation of your arcane power and that you use him to channel spells as well as aid in battle? Or something to that effect

Yes, but you use the stone as a catalyst to summon him using your power (the same power, I assume, is used for the fairies and egi).