As for the school being parochial, no, it most definitely wasn't. It was a renowned school in the nearest-by city — it had a reputation for being quite demanding, and being able to graduate from there was considered a perk — and it was by far also not the only Catholic boys school there. However, in those days — and this is very different now — the school's management was entirely made up of Jesuit priests, several of whom were also active as teachers. Some of the teaching priests — like the one for Dutch and the one for religion in my senior year — were actually quite cool, but not all of them were.
The school had been a training facility for Jesuit priests in the 19th century, and possibly part of the 20th century too, but then it switched to being a generic Catholic boys school — elementary school, middle school and high school — and nowadays it's co-ed and run by laypeople. There was a dorm too, but I never was an intern there — in the sense of sleeping over at the school — because it was only one hour by way of the public transport bus from where we lived.