I know the breakfast is more informal, but is there any etiquette as far as seating or greetings etc go?
Not really. The host should be present the whole meal, and it is customary to personally greet ranking members when you arrive, but other than that it is much more relaxed. Breakfast is provided as a courtesy by Sir Cedwyn to those who wish to partake, not as a formal meal. He's only obligated to feed the guests at his manor.
