Welcome back oakdesign
I like very much both your ideas (buoys and lighthouses) , and I am looking forward to your progress with them.
If you need for help with the dds files, I can provide you with 6 different buoy icons; just tell me how you want them to look as for size, shape and color.
P.S:
What is the advantage of using shp files,? Being vectorial objects they should use lesser memory and should be scalable without quality losses, but as far as I can see from your preview, bitmap icons look also good even at high zoom levels
Are the programs mentioned by you capable to convert text/shapes into vectors, and to export them into csv format?
Last: plotting the coordinates of a SH5 shp file on a plane, I have noticed that they contain several iterations of the same shape/text but at different zoom levels (sort of a mipmap), which is a bit weird talking about a vectorial image. Is this redundant information really needed?