i) Kim was fair in reporting the students as he was enforcing the rules of the school. Latecomers should not be allowed into the school even if they give good excuses as it creates a bad precedent for other students.
ii) The students who were suspended were likely making fun of other students on detention to feel better about themselves and to deflect from their own wrongdoing. They may have also been trying to create a social hierarchy in which they were above those who had to work on detention.
iii) The decision made by the principal seems reasonable as the students were breaking school rules and disrupting the learning environment. However, it would also be important for the school to address the root cause of why the students were consistently coming late and to provide support or interventions if necessary.