What is the scale of the world map? For example how much area is shown from one hex?
The entire map is in the ballpark of 300-400 km across.
What would be a good historical analogy for the technology level? (Late Roman Empire? Early Medieval?)
I'd say something like 1100-1200 for the human civilization, but then there's not really an historical analogy since there's no monotheism, several intelligent species exist, and also there is not a civilization as such since the parts of the land have been isolated until recently. Things are and will be added and removed in comparison.
A good portion of the world-map is adjacent to the sea, presumably the same sea from which humans came to Ravenland. Do you intend to write travel mechanics for sea-faring?
This will probably be limited to small vessels in lakes and along the coast. More might come in a future expansion.
Is there anything more you can reveal about the Rust Brothers? Anything in the way of appearance? I picture them as the reanimated fallen army of Zygofer's betrayal, their armour and equipment ancient and rusted with a range of greens, blues and red hues. Or am I completely off the mark?
Currently the Rust brothers are mostly human, often with a demonic taint, which is considered proper and in line with the prophet Zytera for the devoted. They use demonically tainted creatures and undead which they also tweak. They wear clothes in earthy red/yellow/brown/black, adorned with rusting iron details and often grotesque ceremonial masks. Rusty and smoking iron balls are used both as censers and weapons. There are genuine priests of a monk-like appearance and a fighting order. There might be changes as we develop the game.