UV Image Map Looks Flat.

I have a series of questions about getting my textures to look more realistic. Here we go!

1- When I UV map an image to my models they look a little lifeless like someone just slapped an image on to a model, how do I bring them to life?

2- Can you use multiple UV maps with the same Material? If so how.

3- When I try to texture paint in blender it just paints white instead of using the color I have selected. I suspect this has something to do with selection of a texture white being selected, black being unselected maybe? But I can’t seem to paint on the model.

4- How do I blend two materials together without there being a visible seam on my models?