Short answers, pulled from the story.
King Charles III of West Francia granted lands to Rollo in the year 911 following a meeting at Saint-Clair-sur-Epte. The treaty likely occurred during autumn of that same year after Rollo's defeat at Chartres by Richard of Burgundy.
Richard II became the first ruler styled duke of Normandy establishing the title between 987 and 1006. This development marked the transition from earl to duke status for the region's leadership.
Philip II seized Normandy by force of arms in 1204 declaring it forfeit two years prior. The mainland portions became part of French Royal Domain while smaller Duchy continued under English authority until later treaties.
Scandinavian legal terms embedded themselves deeply within customary laws first written down during thirteenth century. Words like ullac derived from Old Norse útlagr remained current throughout twelfth century usage found Roman de Rou text.
The Duchy of Normandy was permanently united to royal domain after 1469 following a session of the Norman Exchequer on ninth November 1469. A ducal ring placed upon an anvil was then smashed symbolizing permanent union and ending centuries of separate ducal governance traditions.