The color gun allows you to paint lots of objects in the game, along with being able to set custom colors. In addition to this lights can have custom colors. All of this and more is explained in this three part video series.
Quartz is a mineral in the game that is used in communication technologies, aluminum process and also alternate recipes.
Caterium is an ore that you need to research in the MAM, it provides many technologies separate to the HUB milestones.