Essentially, the powers of killing ayakashi and creating shinki will be explained to the god, as will whatever power you have decided for your own character. Whichever god is chosen for you will also be described to them - so if you chose, say, Zeus, the messenger would explain that Zeus is a god of lightning and what sorts of things people pray to Zeus for. You can also assume that any generic question your character might have about the setting will be explained in the way that it is detailed in the FAQ or by mod answers.

The messenger themselves will likely just be a shinki belonging to Amaterasu, wearing white clothes emblazoned with a golden chrysanthemum.

Gods homes are designed by the players of those gods. General descriptions of each home can be found on the Locations page.