Cory

Lunas Both of Sasuke's eyes are intact. The one that was destroyed was Itachi's.

Technically, there is a prequel. The story Kishimoto wrote about Minato. A prequel is merely a story written after the original, but takes place before. It's the same as the Star Wars original trilogy and prequel trilogy. Both follow a different main protagonist, just like original Naruto and the Minato one-shot.

Why would Imu attack the Ancient Kingdom before its people were gone/scattered? A Klabautermann would seek to protect the descendents of those who cared for him so well, out of sheer gratitude. I doubt grief would corrupt such a being to the extent that Imu has been.

The most likely choice is Imu. Imu's ideology seems to align the closest with Rocks and Blackbeard: all three had/have the desire to rule the entire world, to control it. Imu also seems to hate Joyboy more than simply being enemies. It suggests Imu felt betrayed by Joyboy, which sort of fits with the reason Luffy hates Blackbeard, as hurting someone another cares about feels just as horrible to that person as betrayal does. That, combined with Imu's desire, could have been what triggered the war to begin with.

I don't see any reason for their names to be similar. Shanks was raised by Gol D. Roger, while his twin was raised by Garling. Roger hated the Celestial Dragons, so even if he knew Shanks's birthname, he still most likely would have given him a different name, since he may, unintentionally, show irritation toward the name Garling gave him, which could depress Shanks, thinking there's something wrong with him, thus straining their relationship, but, as we've seen, they had a very strong bond.