Short Guide on Importing stuff into Amnesia

[Mudbill]

A quick Google search gives you this about Lamberts and Blinns.

Basically it says Lamberts are plain textures with no specularity, whereas Blinns are more complex. Since HPL adds the specular maps on top of the diffuse, a Lambert is all that's needed.

I don't think you need to recreate the .mat files. I, for example, have several models using the same texture, so instead of having a duplicate of the texture in each model folder, I just have a mat file pointing to a shared "textures" folder with the .dds files. Is this what you're asking?
If you move the texture files, you might have to edit the .mat file if it can't find it.