The man at baldy's side is either his heartless or nobody since they both merged apart. Good thinking, though Xehanort already has a nobody and heartless, ie. Xemnas and Ansem.
Well, about the logic that Traverse Town is made from fragments from other worlds, why are all the buildings made of the same architecture? And was Sora possibly that fragment from Destiny Islands? Because Destiny Islands was destroyed after the second fight with Darkside.
Well, who are the true inhabitants of Traverse Town? Almost everyone you see there was from another world. But there has to be people living in the place for it to exist. Right?
The puppies are not inside or outside his manor. They are in the area where there is a bridge before you enter his manor. You need glide to get to the other side though.
Wow, that is really old. It's probably beta for the game.
Disney Castle was originally going to be a world in the first Kingdom Hearts, but was removed from the game due to time purposes. That's why its icon is still in the game above Traverse Town. Notice also that Donald and Goofy are not with Sora in the Disney Castle scene, but Sora has magic (Look at command menu). Plus, Sora has low HP, probably around the same level when you left Destiny Islands. He couldn't have finished Traverse Town yet because Donald and Goofy are not with Sora and his HP, again, is low. So perhaps the game was originally designed so that Disney Castle would be the second world to play in. But then again, Sora's HP and MP stay the same in almost all the worlds you see. I don't know, just a guess.
Sora didn't see the keyhole either on Destiny Islands. You saw a cutscene of Riku as a child looking at it but Sora never saw nor was able to lock the keyhole. The closest you got to it was at The End Of The World just before the first Ansem battle. You got a cutscene of the island changing and then you couldn't go inside the secret place.
Also, wasn't how Sora got to the Awakening part of the game a pre-rendered cutscene? (Animated cutscene)
I don't remember Riku being on top of the clock tower in Neverland. But I never battled the Phantom so maybe its part of the cutscene before the battle. I don't know about that but those were my thoughts on this.