1. Ryan King Blender tutorials. Also Grant Abbitt. Josh Gambrell for hard surface modelling.

2. Blender's 3D texturing lacks features, particularly if you're used to higher-end 2D painting, and I've found that getting consistent behavior out of its material assignment can be vexing. I've taken up 3DCoat. 3DCoat itself is a complete 3D package. 3DCoat Textura is for texturing. 3DCoat suffers from not enough 3rd party tutorials and general attention, but is a terrific program in active development.

3. For texture work in 2D, I recommend Krita. It's inspired by Fractal Design, now Corel, Painter, and has many similar characteristics, though it's not always identical. It's much more like Photoshop/Painter than GIMP is. Its fundamental intent is original art rather than photomanipulation, so occasionally I end up switching to GIMP, which I hate, to do something in particular. Has a wraparound mode for easy tiling textures. If you work with Krita, go get Rakurri's brush set (available for free, but definitely worth a contribution).