As far as shirt color, if we had a dark color and light color version of the graphics, we should be able to do any shirt color. As long as it is the same order, i don't think that color should matter to these places - maybe I am wrong though.
As far as a pocket - design the front so the graphic fits on a pocket, then it would work on either.
As far as a pocket - design the front so the graphic fits on a pocket, then it would work on either.