as an aside to your second point, there's a fascinating area of study looking at why much byzantine iconography stayed away from things like Pieta and represent

as an aside to your second point, there's a fascinating area of study looking at why much byzantine iconography stayed away from things like Pieta and representations of a suffering/crucified Christ, and stayed much more focused on other themes. Turns out, it correlates relatively well with "where the plague wasn't."