Hello Grandmaster,
First off, I don't think basswood is such a great material for you to carve in...most molds were made of maple or cherry in the old days...much more uniform grain structure.
As for a program to set up your design, you might try MS Publisher... I don't know for sure, but I think you can do what you describe. I want to do something similar to make a stamp to print WG in a circle on the bill. Please tell me if it works. If not, try going to one of those plastic sign shops...they might lay it out for you.
What about making your mold out of rubber? We use RTV (like bathtub caulk) to make molds for producing cultured stone out of concrete...work great, very fine detail, easy to work with, and not too costly. All you need is a GOOD master ...make a coin out of cherry the size you want, wood burn in your info, spray it w/ silicone spray, cover it w/ RTV ...try brushing on 5 or 6 thin coats on each side,then wadding a big, well no more than 1/4 inch,layer on itwhen it is cured, cut in at the edge all the way around, and your mold is ready...
good hunting
David