Welcome to the Mudcat, Kyle!If yo put the word "copyright" in the search box for threads, then set the date filter back at least 2 years, if not 3, there are a bunch of threads which discuss and answer all kinds of copyright questions. I know there is a link, in one of them, at least, to the government website where one can findout more and search to see if a song is still under copyright protection.
I am sure other, more capable than I, will answer your other questions.
Al the best,
kat