You explained absolutely clearly, thank you so much! It helped
Yep, such as John, his manager.
Sire (Sir) was actually the word used to address a King (a superior in general) in the past. We've got the same word in Italian, because it comes from Latin. I think the modern form is "His/Her/Your Majesty".
When John calls Mika "Sire" in the PDP DVD, I think he meant "Your Majesty".
Because he was late as usual.