1. So there would be a (feel free to edit) Dock/Harbor district, Forest/Mountain (FM?) district, Downtown, Slums, and Residential district.
Harbor district: It is divided into two sections; a lowlier, fisherman dominated bay, and a cove taken over by rich nobles. There are many party houses and beach mansions there, and it is an important seat of wealth. The cove is known a Pearl Cove, and it is where the fishermen used to get pearls from. Now, it is a common part trick for foolish young nobles to go diving for pearls and swim among rich flora and fauna located there. The bay is known as the Crystal Bay, called this due to the impressive clarity of the water. It where the fishing society and the dock/harbor are located, and it is where all new arrivals to the city come in. The people there are relatively distant from all the murder and whatnot happening in Keras
Forest/Mountain (FM?) district: A largely natural place. It contains the large forest and the dormant volcano along with the small bit of forest located on it. It is where the nature-lovers and retired elderly live, but there has recently been an outbreak of illness(foreshadowing of the Yellow Mold) around there. There are some private mansions, but they’re usually for displaying wealth rather than living in. It used to be where a lot of the nobles lived before they moved to the Pearl Cove, and so there are a lot of ruins.
Downtown: Where a lot of the Merchant Tycoon’s businesses are located, along with restaurants, shops, stores, and the market. However, it has a dangerous dark side. After dark, the Downtown becomes a criminally infested cesspool, and violence reigns supreme. However, in the morning, it is a busy workplace. There is an unspoken rule among the civilians and the big time gang members that the gangs will not be present in the daytime, and the civilians will not be present during the nighttime.
Slums: A small district, and yet the most populated one. It’s where people go to get forgotten, and there are some illegal slave rings that go on. Children, there are often kidnapped, and a lot of people there are those with nowhere to go - those who cannot work (elderly, disabled, young, criminal, addict, etc.) and those who work the lowest paying of jobs (mainly the workers being taken advantage of by the Merchant Tycoons). Many of them have little or no education. A lot of small-time gangs start up there, and the living conditions are terrible. However, there can often be a strong sense of unity found among the communities there, and everyone shares in order to survive.
Residential district: Where all the normal civilians live. These people make their livings off of working hat shops, selling fruit at the market for the Merchant Tycoons (whereas the people living in the slums would be the ones picking the fruit), and teaching at schools. Many of these people are paying various gangs to keep themselves safe from violence and the gangs themselves. It consists of houses, schools, libraries, and other public facilities.
2. How about Erebus? I feel like calling it Erebos tho because that sounds… better… in my opinion. For the bridges, I think that they are also “spirit energy”, and as such is part of what the corruption magic is trying to destroy. They didn’t cause the imbalance all by themselves, but they were part of it.
I feel like users of Erebos would also be able to use magic like a human would be able to, charms and enchantments and whatnot. The Erebos urges them to consume it, but they're smarter than that and know it will help them in the long run.
3. The former. Of course, the monarch would inevitably stomp around the city and set people on fire, but the main problem would indeed be the volcano erupting.
4. Who wants the boss villain? I name him Theobald Howard Colbert. Also, we know how he's opening the bridges, but they close right after he does so. Does he plant a little magical device or enchantment that will make it open at his command? If so, does he have to enter the realms? Why does he have Erebos? What is his story
5. Okay, so what are the different countries like? I keep on coming back to this, ha. Also, what are the realms like? We somewhat have a basis for Abaddon, and I mentioned before that the realms would probably not be the nicest places to live in (war, dictatorships, natural disaster).
6. What do the spirits look like? How did they make the bridges? Kind of ties back into the "how does their magic work" sort of thing and Q #4.