> We will be able to change the colors and stuff just like your NPC Tool, right?
Yes, the textures, color palette and even the 3D model are part of the DLC.
Edit the first two using MSPaint/PBrush or other BMP editors like NPC_Tool.
No 3D model editing in the first version, but you can steal the 3D models from existing items if they are small enough (eg: black rook 3D model and textures used as a golden axe:
http://www.aibohack.com/wii/chess_axe.jpg )
> Also, will we have the ability to re-name DLC, or no?
Not for the official DLC (red Pikmin hat and top). That will cause possible conflicts so I'm restricting editing (but you can add and delete them).
For newly created items (which can start from one of many 'prototypes') you can name it anything you want. If you want to be fancy, there are 9 different names for the different languages.