I believe you don't need most of the class methods.
Please refer to this article:
http://devs.x-cart.com/en/basics/skin_module.html
Also, please check if you see your class files copied to the var/run/classes/ directory.
Sometimes when you have a wrong file or classname, or when the namespace doesn't match the file path, class files are ignored during the re-deploy process. This might happen in your case.