you picture a tile with 2 black and 2 white squares...would that give me a 6" checkerboard design, instead of the normal 12" checkerboard? have pretty small bathroom, so looking for a smaller square pattern. also should this be laid on an under lament? The floor there now is an old tongue/groove wood flooring.

This tile will be a 12" square tile with a 4 square pattern each at 6"x6". No, you do not need an underlayment however you will want to make sure all planks are secured by nailing or screwing the floor down. Countersink each nail/screw and fill with latex. The surface needs to be completely clean and free of pain, varnish, or wax and completely seal all areas with a suitable latex sealer.