Paint not showing up in Cycles? Today I imported an .OBJ (Along with .MTL) and selected Material and/or texture (As I tried multiple times) and used texture paint - Nothing was showing up at all, just the original color of the terrain when I imported the OBJ, even in the rendered mode. How do I fix this?

I also would like to know, can I use a material and a texture on an object at the same time? Because I'd like to create a glossy look to the water while painting it with a better blue color. 

The link for the .blend file is down below. It just imports with a green color, the color of the grass.

Here it is:
This is an anser to your second question.

Yes, you can have textures and materials at the same time. In fact, you can't have textures without materials.

In cycles, you add an image texture node (found in texture, image), and then you select the path to your image, and simply connect that into the color input of the shader you want to color (or node that you want to input a texture to)