Short answers, pulled from the story.
Concerns were expressed about the suitability of the ageing Bellerophon for the long voyage to Saint Helena. Northumberland was selected instead, and Napoleon was transferred from Bellerophon to Northumberland in Tor Bay, Devon.
Northumberland escorted Napoleon to Saint Helena between August and October 1815. Napoleon had surrendered to Captain Frederick Maitland on the 15th of July 1815 and was transferred to Northumberland in Tor Bay before the voyage south.
Captain Charles Ross commanded Northumberland during Napoleon's final voyage to Saint Helena in 1815.
Northumberland was converted to a hulk in February 1827 and returned to Deptford, where she had been built, to be broken up in 1850.
Northumberland participated in the Battle of San Domingo in 1806, where she was damaged and suffered 21 killed and 74 wounded. That casualty count was the highest of any British ship in the battle.
HMS Northumberland was launched on the 2nd of February 1798 at the yards of Barnard, Deptford. She was a 74-gun third-rate ship of the line of the Royal Navy.