You can't always edit the alpha file. If you black out the alpha file and the mesh isn't flush with the skin, then the skin texture jumps out onto the clothes or hair. Some of the newer Maxis Body Shop items are alpha-editable, a small number of custom creations are, but if you play with the alpha and get skin color where the clothing color used to be, the only way to get what you want will be to learn how to mesh.
The grey stuff is your bump map. Lots of good information in the Wiki here on bump maps. Not every item has one, but if you're changing a texture, you're probably going to have to do some work on the bump map, too.
Uh... I hate to be a drag, but is there anyway you could get the pictures workign again? Being a teacher, you probably know about learning methods. I for one am a visual learner, and I'm finding all your tutorials difficult without the pictures.