A word of advice to waygooks concerning number 5: "Do not interrupt grown-ups who are speaking with each other unless there is an emergency. They will notice you and respond when they are finished talking."
I still followed this advice when I first got to Korea, and my co-workers interpreted it as rudeness! As the younger teacher, I'm supposed to greet older teachers first, even if they are deep in conversation. Yikes!
As a don't-speak-unless-spoken-to child, I find this piece of Korean culture the most difficult to adapt to.