Elliebelly has created 3 new quest guides for the new quests on Hellbound Island. These quest guides are works in progress, but can still be very helpful with information about the quests.
To The Steel Citadel (http://lineage2.stratics.com/content/library/quests/index.php?id=15247) - Level 76
Matras Curiosity (http://lineage2.stratics.com/content/library/quests/index.php?id=15246) - Level 76
Jude's Request (http://lineage2.stratics.com/content/library/quests/index.php?id=15248) - Level 78