It might help to be a bit more specific, because some of these requests are kind of broad:

NoelCan: Lighting and materials are top of My list.

Lighting basics, or the newer lighting features? What about lighting has you the most stumped?

Believable3D: Detailed but intelligible instructions regarding the Material Room.

I hear you on this one. The challenge with the material room, though, is that there are SO many options and so many different uses for a material node that it's not quite as easy to deal with. The material room can be an entire book and a half in itself! LOL  So if you have some particulars that you need to learn ... skin shaders, clothing shaders, metallics, etc etc etc, that would help with a start.

Believable3D: Detailed but intelligible instructions regarding the Hair Room.

Have an example of a specific type of tutorial that would be helpful for you?

BloodRoseDesign: Good instructions that cover bringing a face pic onto a Poser model, something that doesn't look incrediably lame.

Are you talking about using the Face Room, or using some other third party application like Photoshop or one of the 3D Painting applications?

hborre: IDL: The theory, the concepts and settings.

Agreed .. and for this one I will definitely try to get some expert input.