Why don't we need to decline "Okul" here? Isn't this supposed to mean "School's rules"?
More like the "school rules" :) We accept both with and without the possessive suffix however
Are "hakkında" and "için" interchangeable in this case?
No and I cannot think of any situation off the top of my head where they are interchangeable.
Got it. Thanks!
"öğretmen okulun kurallarıyla ilgili konuşacak" da eklenmeli
Why not okulun kuralları? Since it is a specific school?