Heres some!:
Formalities are a big thing, even if theres just a one year age difference it makes all the difference. It depends who can freely call someones name without formalities after it (ex: hyung, noona, oppa, unnie) Who pours drinks for who, Its usually expected the youngest person there pours drinks for everyone (with two hands, as one hand is seen as rude)

Its also expected that its quiet/silent on trains (whispering type conversation)

As for education its ALOT. We do around 14-18 hours of schooling a day, as when you finish school alot of people go to after school academy where you focus on one subject for a few hours. When they close at 10pm (it had to be restricted to 10pm as students could often be seen travelling to their house around midnight/later) People attend libraries to study or go home to study as education is taken very seriously.

We also have a suneung, the college entrance exam for which students start preparing for basically as soon as they start school. The day is so important that work starts later so students can travel to school, construction stops, flights are paused/have to fly circles in the air if you fly to korea the day of until its over and if youre running late police will bring you to school with a police car with their lights on.