What religion do they practice/way of life they lead in the monastery?
And what's the rough outline of the hierarchy?)
//and if it isn't too many questions in one: what's the feel of the story, what's the main goal, or is there a reason it's set there specifically (?)
I really love your attention to detail and character designs so much!!
Their religion is called Madonicism and it's basically a fantasy variant of catholicism. It doesn't involve a christic figure, and mostly revolves around a big roster of saints, both common to all and local to each city/region, with various levels of importance. The main saint is the Madon, a three-faced motherly figure. It's the main religion in western europe and it's part of a wider group of religions called cruciphore religions.
The monastery is an Abbey, and it's ruled by a set of two people : an Abbess of the women, and an Abbot of the men. In reality, their functions overlap and men and women share most spaces in the abbey. Sworn brothers and sisters all work in the monastery, and some of them have specific functions like key keeper, librarian, lead cook, lead shefferd etc. The people in the green doublets are Acolytes, young nobles who are only here for a few years to learn to study. Kids in beige are novices.
As for the story itself, I'll keep that for myself for now ! I'm pitching the project at the moment, so you'll have to see :^)