If I remember correctly, they divided the black pearl quest into two "chapters" (although they shouldn't really be considered that), both of which had us recruiting members to help us. There wasn't a difference between them though (other than the obvious).
Looking at the Wiki, you are close to finishing. There are about 3 more people following Gunner. (
http://www.disneysonlineworlds.com/i...o#POTCO_Quests)
As for leadership, the others said everything pretty much. You just have to finish the quest, beat the boss battle, visit Jack, then you are free to use the skill.