I am removing the cultured marble walls from my shower wet area and will first replace the old drywall with greenboard in the wet area and then re-attach the marble walls to the new dry wall. How can I remove the old drywall fron the backs of the marble after I cut them out and remove them? Will I need to scrape, chisel, steam, or something else? Anyone with experience doing this?

I am framing for a new bathroom. All the 2x4 studded walls are in. On one side of the wall, I would like to have a nitch or two. Something like this. [IMG]http://www.woatile.com/images/Specialties15L-Inset-Shower-Shelf-Mosaic-Back.jpg[/IMG] So what I have is a "side wall", studs spaced 16" on center. It can be easily adjusted if necessary. I would like to frame in now a nitch or two. My assumption is when I put cement boards over the wall, the cement board would be cut up and screwed into the "frame" of this nitch and my waterproofing goes over the cement board. First, is it necessary to use pressure treated lumber for this frame? Or it is OK behind the cement board? Second, what is the "typical" height and dimensions of these nitches? Is there a typical? I assume it makes no sense to have one 24" tall, as there is nothing that is that tall that will use this space. So shorter height is better? Is two side by side better than one big one across? I am not asking in terms of difficulty in construction and tiling, but usage and convenience. Is there a typical height to the bottom of this nitch? Would waist height be good as a guideline? and do you ever set it at a height such that it would be a multiple of the tile height, so that you can be at the seam of a full tile at that height? Do you tilt the bottom of the nitch out a little so water will run out? If so, is that done during the framing (now) by tilting the lumber a little, or compensated later using spacer and thinset during tiling? Thanks!