The clone version! The game world could also have Euuripedes, Oedipuus, and Jesuus.
Absolutely.
This may not become clear in-game until Game 3, though there may be some reference to it in Game 2. But yes, intensive Theurgic agriculture strips out nutrients at a faster rate, leading to (eventually) dropping yields and land that can only be farmed by Theurgy.
The acid, arid land mentioned in the game is the Brecks, the pasturelands along the southern border. There is actually some decent farmland around Rim Square (almost all owned by the Keriatou and Pelematou)–or farmland that was decent until overcultivation left it dependent on Theurgy.