In the Spirits menu, one of the toys is spray paint (you find it in chests or buy it), just point at the Dream Eater you want to recolor and then pick the color.
Yeah, some locations don't even appear on the actual map, you have to destroy walls/other stuff to reach them.
Go on the lower part of that map and then jump with the help of flowmotion, there's a kind of hidden middle floor with the chest.
Whatever Xehanort succeeded with Sora or not in DDD, I really hope Sora does become a seeker of darkness in KH3, even just for a short time. I just love it when main characters become evil for one reason or another.
Yes, you can make AR Dream Eaters without the AR cards in the EU/NA versions of the game, but there is no recipe for them, you have to find out the materials yourself.
The location you're missing is Symphony of Sorcery with Riku, in the first area once you enter the musical score.
e: The first area with Riku is called Moonlight Wood, not Cloudwalk.
Plot-wise, the game isn't that important, if you just read the synopsis DDD gives you in-game, you should be good; but it's a good game, with a fun combat system, nice character interaction and the avatar menu is quite addicting.
1) The number on the drop gauge is the speed at which it drops, and there are no commands similar to the Drop-Me-Not/Drop-Me-Never items.
2) Not as far as I know.
And pfff, that's a nice way to finish a post.