Erik is going to remain "King" until Elbreth grows too large to maintain a hold on some places without having them remain a Kingdom.
If Trubaldsome had been given Miring officially, it would have been as a duchy. In that event, the most concession Erik would have made with him would have been to let him keep the title of "Prince" for his line.
Suul was going to be crushed next, but the Zimtar raiders cut to the front of the line for that display in the court room.
After the Archbishop's display of power in Suul I'd be very cautious about bringing any conflict to them. At least until we can rebuild our sapped strength.
The Ztah raiders are a different story, just bring enough flammable liquid to pour into their cave then seal the entrance
We need to hear about the Archbishop's display of power before we can start to consider attacking them a bad idea
But I think we have Suul trumped in pure military strength. If Manskinner survives, we'll have him on our side. We'll have the Cyclist order working from the inside and outside of Suul. And then we'll have Elbreth's power (now supplemented by Miring and Preston's manpower and gold). Assuming the Mask is any good at his job (and if Terenos survives, if Terenos is as good at leading infiltrators as he is at being one), and Kain stays on his toes, we should be able to wrestle the espionage aspect of war from Suul's grip.
Finally, we'll just have to change up our tactics a little so as to prevent the Archbishop from using his observations during this war against us.
I don't know how we'll deal with the raiders, but I imagine having a small corp of adventurers and map-makers coming in and out of their cave won't be too good for keeping them hidden. We might even be able to get Suul to aid us in destroying them if someone brings us word of their captive Suulian farmers.
In regards to Erik becoming an emperor: It will probably happen when Erik takes over the Hatcuri Nation.
Ashton is right about business taxes: They're based on whoever owns the land your business is based on/in. As it hasn't come up yet, Elbreth has no special laws for that yet. And since you're in Miring, you'll probably be able to get away with a year or two of work before whoever is Duke even has enough control over the populace to start requiring all businesses to be registered or whatever.