Short answers, pulled from the story.
Copyright in the United States generally lasts for the life of the author plus 70 years. For works made for hire, the term is 95 years after publication or 120 years after creation, whichever is shorter. Works published before January 1 of the relevant public domain cutoff year are no longer protected.
The Sonny Bono Copyright Term Extension Act of 1998 extended U.S. copyright protection to the life of the author plus 70 years. It was nicknamed the "Mickey Mouse Protection Act" because one of its most visible effects was preventing Disney's Mickey Mouse character from entering the public domain.
The Music Modernization Act of 2018 brought all sound recordings under federal copyright for the first time, regardless of when they were made, and preempted state copyright laws on those recordings. The first recordings to enter the public domain under the Act were those fixed before 1923, which did so on the 1st of January 2022.
The idea-expression dichotomy is the principle that copyright protects the specific expression of an idea but not the underlying idea itself. This is codified in the Copyright Act of 1976, which states that protection does not extend to any idea, procedure, process, system, method of operation, concept, principle, or discovery.
In Feist Publications, Inc. v. Rural Telephone Service Co., the Supreme Court denied copyright protection to a white-pages phone book listing telephone numbers alphabetically. The court rejected the "sweat of the brow" doctrine, holding that hard work alone, without creativity, cannot make a non-creative compilation copyrightable.
Willful copyright infringement can result in a fine of up to $500,000 or imprisonment for up to five years, or both, for a first offense. Repeat offenders face fines up to $1 million and imprisonment up to ten years. Felony penalties for first offenses apply starting at seven copies for audiovisual works and one hundred copies for sound recordings.