cds melt, so you need to have something between layers or you won't get them apart. I have used layers of thin ply, I have heard others use cardboard. You also need to be a little careful sanding, the film comes off easily.
as for thin wods to use for jewelry. 1/8" hard woods work really well. I have used maple, walunt, cherry, wenge, narra, purpleheart, teak and many more. It important to look at the grain direction of each piece of wood in relation to the design you want to cut.