The city is a merged version of many cities, its original name forgotten. Due to the biases of the builders of this mush, the cities will be American in flavor. Since the End, no children have been born, and no one ages naturally, so everyone plays someone at least 50 years old, altough part of that time may have been spent in a coma, as a ghost, or in magical stasis. Yes, the City is currently under the domination of the infernals. The Citadel Lord is a Demon.
Angels are only present as individuals.
They are not supposed to openly war against Hell at this time, but they can interfere upon the request of humans. About what you would expect from 1999. Nobody had the time or energy to spare for research after the End hit. Massive earthquakes and plagues killed off much of the population. You are lucky to still have electric power, and a few working factories.