Short answers, pulled from the story.
Dudo of Saint-Quentin was a Picard historian and dean of Saint-Quentin, born in the 960s. He was sent on a diplomatic mission to the Norman court in 987 and became the author of the Historia Normannorum, the earliest major history of the Normans. He died before 1043.
The Historia Normannorum, also known as Libri III de moribus et actis primorum Normanniae ducum and Gesta Normannorum, is Dudo's history of the Normans written between 996 and 1015. It covers Norman history from 852 to the death of Duke Richard I in 996 and is written alternately in prose and verse across four parts. It was dedicated to Adalberon, Bishop of Laon.
Dudo's reliability has been disputed since the medieval period. Historians such as Ernst Dummler and Georg Waitz regarded the Historia as untrustworthy because Dudo relied on oral tradition rather than written documents, giving it the quality of a romance. Others, including Jules Lair and Johannes Steenstrup, argue it still holds considerable value for understanding Norman history despite its legendary elements.
Dudo recorded that the inhabitants of Bayeux more often spoke "Dacian" (old Norse) than "Roman" (Old French). He also claimed that Richard I of Normandy was sent by his father William I Longsword to learn the Norse language from a teacher called Bothon.
Dudo obtained his information primarily from oral tradition rather than written documents. A large portion was supplied by Raoul, count of Ivry, who was a maternal half-brother of Duke Richard I of Normandy.
The Historia Normannorum was first published in 1619 by Andre Duchesne in Paris as part of his Historiae Normannorum scriptores antiqui. A further edition appeared in the Patrologia Latina in 1844, and the edition considered most authoritative was edited by J. Lair and published at Caen in 1865.