Interest topic, but not much official yet. Here my personal thoughts:
1. Possibly, blood infections from open wounds, because most dead comes from duels, combats or monster hunts, at least from gameplay-view; And of course unknown plagues like the oja plague.
2. Both. If they closed Ojaveda because of the plague there, it should be an illness that can get everyone. But of course, races are different. Especially Kran may have own illness in their special silicon-organism and are safe against most infections from other races.
3.I think, because its still a medieval world, most mental illnesses would be seen as curses or god-willing. I'm not sure, but maybe alchemists and mages could try experiments or the society avoid these people.
4.Complicated.
5.Maybe. There's a yliakum wide main language or not? At least i use "modern yliakum standart ylian" (english). Don't know what's called officially. If there's a sign language, its official, i think becaue yliakum has ONE government, he inner circle (octarchs & vigesimi)
6.Is there a school for all? Maybe if a guild support such social work like school for disabled. The order of Light may would do
These are no facts, just what i would imagine.
