I believe your are looking to decal within Poser as opposed to adding your number or text  to the original texture in a 2D program.  Here are 2 tutorial links on how to address it:

http://artzone.daz3d.com/wiki/doku.php/pub/tutorials/poser/poser-maps05

http://www.superheroinecentral.com/mrx/xpage/decaltutorial/decaltutorial.htm

Can't answer your second question, but some one more familiar with the process may elaborate.