This is all off the top of my head, so don't hold my feet to the fire:

You can use image maps (or generate procedural textures) plugged into the diffuse_color node. This will be the main texture that is applied to your mesh.

Specular_color is, as you say for the "shiny parts."

Bump Maps will give an appearance of roughness, uneveness, etc to the surface. They are greyscale maps where white is the highest and black is the original surface. They do not actually modify the surface, just it's appearance.

Displacement Maps actually cause polygons in the mesh to deform. They work the same as bump maps with black being the original surface and white being higher. You must check  the displacement maps box in your render settings for this to work.

Transparency Maps are often based on a greyscale alpha channel made from the texture. Black in this case is invisible while white is opaque. Transparency edge determines the opacity at the edge of a transparent object and is somewhat determined by the "thickness" of the object. Look at a thin wine glass and compare it to a thick water tumbler.

As far as settings go, I'd highly suggest you take an evening and play around. Most settings are so dependent on all the other settings so that there are no hard & fast rules to tell you. Apply your materials, render in the little window, make a change, render again and slide the little triangle back and forth to see the differences. Make a big change, render and compare. It won't take you long to see what the different settings do and how much is too much. Have Fun!

HTH,

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