I'm not really a character guy, so there's not much on characters on the wiki. Check the examples section though, some good stuff there. http://wiki.polycount.com/wiki/Character#Character_Examples Like this: http://wiki.polycount.com/wiki/Roguedevelopmentdiary Also some stuff…
Very likely decals, yes. We have some info on our wiki. http://wiki.polycount.com/wiki/Decal http://wiki.polycount.com/wiki/MultiTexture#Modulation_Blending
Here's a walkthrough of one artist's process. http://wiki.polycount.com/wiki/Roguedevelopmentdiary More stuff here http://wiki.polycount.com/wiki/Character
Some more links that might help you http://wiki.polycount.com/wiki/TexturingTutorials#Painting_Stylistic_Textures http://wiki.polycount.com/wiki/EnvironmentSculpting http://artbypapercut.com/
As Joao said, check the Wiki link up top. Some links to get you started: http://wiki.polycount.com/wiki/Texture_Baking http://wiki.polycount.com/wiki/Polygon_Count