How do you copy a novell user and their memberships to a new user account or even an existing user?

You don't.  There is no copy.

You can create a template based on the user, and then use the template to create the new user account.  

If you right-click on the OU in which you want to create a template, select "New > Object..." and choose "Template" from the list of object types, the new template dialog box allows you to use an existing template or user object as the model.  

It will not carry all attributes over from the source user object, but it will carry group membership attributes, restrictions, login script,.   It will not assign filesystem rights to match the source object via the "rights to files and folders" tab, so that would still have to be done manually if you aren't assigning rights by group membership or inheritance.

After creating the template, you will want to remove anything specific to the template's source object like home directory, or "other name," for example.

You could use the new template for any number of new user creations, and if there are specific filesystem or NDS rights you want the new user objects to have explicitly granted, you can add those in the "new object NDS rights" and "new object FS rights" tabs.

Adding a user to a template won't affect their group memberships - nothing is inherited from a template object.  "Members of template" list is for information only and is intended to list users created using the template.