That’s correct. EG is a port town where a significant share of local income and trade comes from fishery and catching Great-Eels (actually a giant sea mammal) and rendering their blubber into the eel-oil mentioned a few places in G1. C is cropland, I is intensive irrigation, generally found in major river valleys or where Theurgy facilitates higher than usual rates of water extraction.
Can’t believe you actually counted the boxes. 
As ever, having you put such time and care into analyzing my work is both humbling and a joy to read.
Soretto is a big city, the fifth biggest in the Hegemony (after Aekos, Shayard, Corlune, and Eskydra) but only about half the population of Grand Shayard, which benefits from being the governing center of the Hegemony’s breadbasket.
They won’t go back to a land that can’t feed them.
Shaping earth and stone into a house that will actually stay up when the Theurgy stops would be tremendously blood-intensive. Theurgy can be a quick way to get ditches and ramparts, but isn’t an efficient way to build buildings.
Not a novel species – just already-domesticated beasts that got caught in a Storm.
The realm was named for the city of the conquerors, so the city name doesn’t really work as a metonym. For the others, a seat of government can be a metonym for the current ruling claque, but not for the nation itself – not at this early stage of pre-modern proto-nationalism.
You’ve got the option to try! Worth noting that the Floating Palace is not Aekos – you couldn’t fit the millions of people who live in Aekos onto a single flying hill without it turning into the Floating Favela. (As it is, the biggest slums of Aekos are in the shadow/drainage zone of the Palace.) Whatever happens to the Palace won’t directly crush most of the city.
The best porphyra dye is made in Shayard, on the coast of Leurs and Bragat-Laconne south of Corlune. As Laj-jas will explain in Ch 3, some Abhuman clans would refuse to use it, considering the tens of thousands of snails a wasteful consumption of life…while others, like himself, luxuriate in it.
A tremendous amount; as you’ll see next chapter, the Shayarin of the yeomen of Irduin is quite different from the Shayarin you grew up speaking in the Rim. A family of dialects like Arabic is a terrific way to think of the language. The massive-scale trade in grain and helots has helped to smooth out some of the language difference that would otherwise have persisted, in large part by a steady Koine-ization of Shayarin. “Earlund” and “Brimlund” would themselves be abstractions covering over a huge amount of diversity.
When the Hegemony’s central authority collapses, the “natural” outcome would probably include Shayard splintering into a number of successor states, somewhere between its 5 subregions and its 60 aristarch-led districts (and with border areas like Avezia, lowland Wiendrj and the hill country between Veldrin and Chaton also in play).
Keeping a single Shayard more or less in its current boundaries will be possible, and building a strong “homelander” coalition will definitely be helpful in this – but in keeping with @Zincvit’s and @Ramidel’s observations, that will involve overcoming both regional identities and irredentist overreach to end up with a sustainably sized realm.
“Scout for opportunities to raid the institutions of the Hegemony,” and “Tax collectors—a mission so sensitive it will require my personal involvement.” To get the storyline that leads to the Xaos-lands, you’ll need to kidnap a tax collector’s family, and have him end up dead.
