The Cullavagga includes an elaboration of the bhikkhus' etiquette and duties, as well as the rules and procedures for addressing offences that may be committed within the Sangha. Also included is the story of the establishment of the bhikkhuni Sangha, plus detailed accounts of the First and Second Councils.
The passages listed below follow the numbering convention used by I.B. Horner in her PTS English translations.
Cv 5.6: A Wish of Loving Kindness [Olendzki]. These lesser-known verses of metta (loving kindness, good will) illustrate the Buddha's skill at adapting an existing tradition (here, protective charms against snake bites) to serve as a vehicle for a more universal teaching.
Cv 8: Vatta Khandaka — Collection of Duties Thanissaro. This chapter concerns the duties that govern the day-to-day life of the bhikkhus. Many of the duties outlined here are more subtle than the strict rules laid out in the Suttavibhanga, and call on the bhikkhus to cultivate a respectful and well-mannered sensitivity to others in the community. Although this text is principally intended for monks, laypeople will find in it many useful hints for the mindful cultivation of good habits and manners, even in the midst of a busy lay life.
The Buddhist Monastic Code, Volume II: The Khandhaka Training Rules Translated and Explained, by Thanissaro Bhikkhu (Valley Center, CA: Metta Forest Monastery, 2007).