Important Books

definitely read these if you can
Pathfinder Adventure Path: Skulls and Shackles Player’s Guide (free dl from paizo.com. Highly recommended you read it)
Pathfinder Player Companion: Pirates of the Inner Sea (pirate class/equipment/options)
Pathfinder Player Companion: Sargava, The Lost Colony

base game rules, all of it is applicable
Pathfinder Core Rulebook
Pathfinder Roleplaying Game Bestiary (player races)
Pathfinder Roleplaying Game: Advanced Player’s Guide (new character options)
Pathfinder Roleplaying Game: Bestiary 2 (player races)
Pathfinder Roleplaying Game: Ultimate Magic (Classes/Feats/Equipment/Achetypes
Pathfinder Roleplaying Game: Ultimate Combat (Clases/Feats/Equipment/Archetypes)
Pathfinder Roleplaying Game: Bestiary 3 (player races)
Pathfinder Roleplaying Game: Advanced Race Guide (races/archetypes/feats/archetypes)
Pathfinder Roleplaying Game: Ultimate Equipment (equipment)

I own these, though not directly related, they can help
Pathfinder Player Companion: Adventurer’s Armory (equipment)
Pathfinder Player Companion: Humans of Golarion (information on ethnic groups)

do not own, let me know if you want to use these
Pathfinder Player Companion: Dwarves of Golarion
Pathfinder Player Companion: Gnomes of Golarion
Pathfinder Player Companion: Orcs of Golarion
Pathfinder Player Companion: Inner Sea Primer
Pathfinder Player Companion: Halflings of Golarion
Pathfinder Player Companion: Faiths of Purity
Pathfinder Player Companion: Faiths of Balance
Pathfinder Player Companion: Goblins of Golarion
Pathfinder Player Companion: Faiths of Corruption
Pathfinder Player Companion: Blood of Fiends (tiefling)
Pathfinder Player Companion: Blood of Angels (aasimar)
Pathfinder Player Companion: Kobolds of Golarion

Important Books

Skull & Shackles (Mavrickindigo) Mavrickindigo