Other InfoAll dialogue will be shown in speech bubbles. They won't be spoken when the world is in retro form, because video games didn't have voice acting then. There will be closed captioning, and voice acting in the regular world, though.
The Marshmallow Gun will be found at the end of the Dallas world.
The ticket will be found after defeating the boss of the New Orleans world, and will take you to Newark, NJ.
In the regular world, it will have normal music, but the music will change into 8-bit after the world changes.