As other people have said, I don't know why everybody is complaining about the complexity! It's really not that hard. However, unlike most (crap) movies that come out nowadays, you actually have to WATCH it. If you are going to snuggle with your girlfriend (or boyfriend), or if you leave to take frequent bathroom breaks, YOU WILL BE LOST. But don't blame the movie for that. There are just a few things you need to keep in mind while watching, and the rest will explain itself (if you pay attention). I won't mark spoilers, since they all apply to the first 30 minutes of the movie.
* Jack's deal with Davy Jones included both himself and the Pearl. That's why the Pearl is with him in the Locker.
* In both 1&2, they repeatedly say that the Black Pearl is the fastest ship in the world. Because of that, it is the ONLY ship that can outrun the Dutchman. That's why Will needs it.
* The council had not yet been called when Tia Dalma brought back Barbossa and suggested that they resurrect Jack. The council can only be called when "the song" is sung, which they say repeatedly in the movie. Therefore, the council was called in the very first scene of the movie, when the kid was hung. In fact, that was the whole reason that Beckett started hanging people! He wanted them to sing the song so he could hunt the Pirate Lords in one location. Also, the song tells the story of Calypso, if you listen to the words.
Now, for the spoilers....
* The Calypso thing was not "thrown in" as some people suggest. If you paid attention during Pirates 2, Tia Dalma had an identical locket to Davy Jones. Therefore, that particular character would have to be over 200 years old! And she didn't just disappear either. She said to Davy Jones that she would release her cruelty on the Pirate Lords for sealing her. Then, when Will revealed to her that it was because of Davy Jones that she was sealed, she went ballistic and created a maelstrom in hopes of impeding both sides. When Jones was killed and sent down to the sea, her anger was abated and the maelstrom stopped.
* There is a false Calypso in the movie. When Barbossa told Sao Feng that they had Calypso, he noticed that Feng's gaze went immediately to Elizabeth, instead of Tia Dalma. He then dropped a few lines to encourage Sao Feng's wrong line of reasoning so that Feng would bargain for the wrong person.
* Barbossa's purpose was not to provide one of the 9 pieces of 8, since they already HAD his piece. He struck a deal with Tia Dalma that he would sway the coucil in favor of releasing her in exchange for a second chance at life. JACK'S purpose was to provide the piece. That's why Tia Dalma seemed so excited to help them get Jack back in the second movie.
* They couldn't bring Governor Swann back because he was resting in peace. Tia Dalma said this when Will asked if there was any way.
It was all there. I didn't read any outside sources. I just watched the movie. For those that found it too confusing, I would encourage you to watch it more carefully. They weren't trying to make a movie that could be watched and forgotten. They were trying to make a movie that grew on you the more you watched it.