Short answers, pulled from the story.
The phrase Christian name appears in Elizabethan England as a term for any given name, not strictly tied to baptism. William Camden observed that these names distinguished individuals while surnames separated families.
Scholars debate whether early Christians adopted new names immediately following baptism based on apostolic tradition. Modern historians reject the idea that changing one's name was an automatic requirement of becoming a Christian in the earliest days.
The martyr Balsamus declared in AD 331 that he bore the spiritual name Peter after receiving it through baptism despite his paternal name being Balsamus. King Caedwalla traveled to Rome where Pope Sergius baptized him and renamed him Peter shortly before his death.
Around the year 1200, William stood as by far the most popular Christian name within England itself. Lists from legal proceedings edited in modern times show that ordinary names like William, Robert, Roger, and Geoffrey remained common throughout the Middle Ages.
Mary was rarely used as a girl's name in England during the 12th century before eventually rising in prominence. George saw little use in the 13th and 14th centuries until growing in popularity following the Protestant Reformation.