I know this is an old thread I've stumbled on, and this isn't about your software (I am not technical enough to comment), but on your copyright statement.
If you say: "This file is free of copyright" you are dedicating it to the Public Domain. Essentially this statement has emancipated your work from the "protection" of copyright. But what you say after indicates that is not what you want to do.
The many and varied licenses (the most famous being the GPL and Creative Commons) that have sprung up to mitigate the insanity of patent and copyright law in recent years, restrict or empower as desired by using copyright law. Copyright law is what allows the license to have "teeth." Once you renounce copyright, you also renounce any ability to apply restrictions.
It sounds like what you want is a Creative Commons Attribution Non-Commercial Sharealike license (CC by-nc-sa) People do write their own licenses, of course, but one should be very well versed in the law, or get legal advice, before doing so, if you want to be sure of the ground. Using an untested license places your work at the mercy of the law courts, which can range very widely these days.