Works are protected by copyright as soon as they are fixed in a tangible medium. Protection varies by country, but most are based on the Berne Convention, which requires automatic protection for the life of the author plus 50 years; the US and some other countries have extended this to life plus 70 years.
Not since 1978.
Not necessarily. It's the year the item was copyrighted, which may be different than when it was actually made.
One must apply to the copyright holder for permisson to use their copyrighted item.
Yes, if you have used it without permission from the copyright holder or an exemption in the law.
Bootlegging alcohol, yes. Bootlegging trademarked or copyrighted material, it depends on the item that was bootlegged in some cases.
No; the act of changing it would be infringing on the creators exclusive right to alter the work and create derivatives.
We can't answer questions from printed/copyrighted materials. You could ask about each item you have in mind separately.
Yes; plagiarism is passing off someone else's work as your own, which would include works in the public domain.
Using an excerpt that is "appropriate in kind and amount" for purposes such as criticism, comment, news reporting, teaching, scholarship, or research.
If you created it, you hold the copyright. To help enforce that right, you should clearly mark the item as being copyrighted. To bring a lawsuit, you will have to copyright the item through official channels through the Copyright Officer of the US Government.
Yes. The clothing you make isn't copyrighted - only the pattern you bought is.
Only if the copyright is not part of the copyright registration that is copyrighted in the publication of the author's registration. But If the copyright is part of the copyright registration that is copyrighted in the publication then the copyrighted author of which publicized the copyrighted registration is not copyrighted in the legalized sense of which a publication is copyrighted. Yes, a work is always copyrighted, before and after editing and both versions.