Short answers, pulled from the story.
The modern English word Easter derives from a pre-Christian source named after the Germanic goddess Eostre. The 8th-century Anglo-Saxon monk Bede recorded that the month of April was once called Eosturmonath, or the Month of Eostre. This name was adopted by the English-speaking world while the rest of the Christian world used the term Pascha derived from the Aramaic and Hebrew word for Passover.
The First Council of Nicaea in 325 AD marked the turning point in the history of Easter by establishing a unified method for calculating the date of the resurrection. Emperor Constantine convened the council to resolve the Easter controversy and decreed that Easter should be celebrated on the first Sunday after the first full moon on or after the vernal equinox. This decision effectively severed the direct link to the Jewish calendar and required Christians to calculate the date independently.
The divergence between the Julian and Gregorian calendars has created a persistent gap in the date of Easter between Western and Eastern Christianity. The Roman Catholic Church adopted the Gregorian calendar in 1582 to correct the drift of the Julian calendar, fixing the equinox on the 21st of March. Most Eastern Orthodox churches continued to use the Julian calendar, which is now 13 days behind the Gregorian calendar, causing Orthodox Easter to fall on the same day, a week later, four weeks later, or even five weeks later than Western Easter.
The earliest Christian tradition of the Easter egg originated in the community of Mesopotamia where believers stained eggs red to commemorate the blood of Christ shed at his crucifixion. This practice evolved into a widespread custom of decorating eggs, with the oldest tradition involving dyed chicken eggs. The House of Fabergé workshops in Russia created famous jeweled masterpieces for the Imperial family from 1885 to 1916.
The Puritans in colonial New England viewed traditional feasts like Easter as abominations and argued that the Bible does not command their observance. The Religious Society of Friends or Quakers believe that every day is the Lord's Day and were persecuted in the 17th and 18th centuries for their refusal to observe Holy Days. Jehovah's Witnesses maintain a similar view and observe a yearly commemorative service of the Last Supper and the execution of Christ on the evening of Nisan 14 known as The Memorial.