I am installing ceramic tile over 1/4 inch cement board in a small bathroom. Do I really need to glue the board down with thinset or are screws enough to hold it down? The cement board is going over lap board, tongue and groove, and old, intact linolium. Also, I am using 2 inch square tiles that are dot mounted. Can I use regular tile adhesive to set the tile, or will it squeeze up too much in between the tiles and cause problems when I grout? I know with mosiac tiles you should use epoxy as both the adhesive and grout. I'd rather not deal with epoxy if possible.