Generating UV maps via Unity

Hey there fellow developers ! I am Richard. I have this question / problem I am trying to solve.

At the moment I am trying to find the best method for creating my models. I am using blender as it provides me with comfortable tools for UV mapping but I encountered a problem during the normal and spec. maps section. If I try to make my UV a normal map and use it in unity 3D I get broken edge thingy. ( meaning the edges of a mesh is white or in any other color. I could make my meshes look just the way I want through a couple of different materials but UV map is essential for optimization of my meshes as any others.

My question is this: Can I for example take a box mesh and make it in 6 colors ( 1 color per face ) apply 6 different textures to the box for each side. At this moment I would have 6 different material with diffuse, normal and spec maps. And then save this whole beauty as a UV map in unity? so that I instead of 6 Mats. would have only 1 therefore only 1 draw call per mesh... As I know you can generate Light maps via Unity can you the same with mats?

Thank you for you answers !