Fade from one material to another.

I have a model and I want to make a demo reel.

I want to fade from a plain white model (with only diffuse shading and ambient occlusion) to the finished model (with SSS, bump maps, texture maps, specularity etc.).

How do I do this?

Also, if I want to display the wireframe on top of my model, do I need a second copy of my mesh (like he does here), or does blender have an option or slider I can manipulate?

Render animation with both materials and then fade between the two clips in editing.

For wire renders you don’t need a second mesh. Use the 4th method in the original tutorial that uses a combination of two materials (one wire and one solid) on the same object http://blendtuts.com/2010/08/how-to-render-wireframes.html