1) I am assuming that Coronian culture is basically Generic Fantasy Europe with a side of Whatever The Hell Akashima Is. Yes?

Yes. And Akashima is a lot like Feudal Japan with all the spiritual trappings of Shintoism and other myths.

2) What's the state of magic in Corone? Both in the Empire and the Rebel cities.

General. Very vague. There is no Althanas magic that I know of that has originated in Corone.

3) What's the overall tech level of Corone? Roman, Medieval, early Enlightenment?

Medieval

4) Looks like Gisela went Empire. Who owns what?

Nope. It belongs to the Rangers unless Letho and Elrundir decide to finish that quest of theirs.

5) Who's on what side? Aside from the durhurhur obvious ones like Letho. Better yet: Is it even important to know?

Player-wise: Everyone wants to be a boy scout, everyone wants to be a hero, everyone wants to be Letho Jr.
... Just sayin'