This final area is long and fairly dangerous, culminating in the final fight of Chapter 11. You'll find Bhakti's fifth part early in the area, and it's highly recommend that you backtrack and repair Bhakti immediately. The rewards are substantial, especially if you've spent some time exploring, and you won't get another chance to complete the sidequest until you can return at the end of Chapter 13.
The actual bridge is basically straight, and there's not much to miss. Once you see the Ethersol near a save point, you know it's time for a boss fight. Note that you can choose to keep exploring Chapter 11 after defeating the boss, provided you don't take the ship that appears. This allows you to fight in Chapter 11 with Crystarium Stage 9 unlocked, if you're so inclined, but there's really no compelling reason not to move on to Chapter 12.
The actual bridge is basically straight, and there's not much to miss. Once you see the Ethersol near a save point, you know it's time for a boss fight. Note that you can choose to keep exploring Chapter 11 after defeating the boss, provided you don't take the ship that appears. This allows you to fight in Chapter 11 with Crystarium Stage 9 unlocked, if you're so inclined, but there's really no compelling reason not to move on to Chapter 12.