Part 2
See Wikipedia article on "Eastern Orthodox church architecture," with the distinction of sanctuary, nave, and narthex towards the end.

Traditionally, Byzantine churches have paintings of saints on the wall of the nave and sanctuary, as well as the iconostasis, leading to the pious conception of the whole inside of the building as "heaven" or "heavenly sanctuary." Don, you may have encountered such usage somewhere, and took this to mean the entire church was understood as sanctuary. I also see in the Wiki article a reference to a practice of calling the altar a throne, a pious practice outside my experience.