YES, my bad, I should have indicated a thin layer of adhesive between the plywood and cement board. Stabilizes the floor. I hold the tile back 1/4" from the bottom plate of the wall, then cover the gap with the baseboard. Some people like to use caulk along the line of the tile and baseboard to seal mooisture ... but I find it gathers dust.
Also, if you are using larger tiles, I back-butter them before dropping them down. This guarantees best adhesion. If you are installing travertine, this step is a MUST because there are so many voids in the back of those tiles.