The basics of the plugin are now working. I can create, save, edit and delete Creation Caches. I can also display these through the website. I have found out how to style these elements, to make them look good. I have developed a system for creating the star ratings for difficulty and terrain, just as found on the geocaching website.
However, the only way I could achieve display was to create a template file, called single-creationcache.php, which hade to be located inside the theme that I am using. Now this is not satisfactory. I need to find a way of keeping this template inside the plugin directory.
Also still required is a method of displaying an archive of these creation caches. I could probably do this by putting a template in the theme, but, again, I want to find a way of doing this without resorting to that method.
A second job still required is to find a way of dsplaying the creation-type information (my taxonomy).
Finally, I have not yet produced the .gpx and .loc files. I would like to do this on-the-fly, and enable the file to be deleted again, when leaving the page, or by some other means.
Please see GitHub below for the latest code.
STOP PRESS: I have solved the Template issue!!