Very nice summary. Being a (very) small publisher myself, I already knew all this, but it’s astonishing how many writers apparently don’t. The “poor man’s copyright” thing is particularly vexing. No matter how many times it’s debunked, no matter how much one points out it’s basically a waste of postage, people will insist that it’s better than nothing.

One small clarification. You write, “In other words, for writers copyright means that you own your work and no one else can legally claim it’s theirs unless you authorize them to.” This is correct, but it actually means more than just that. It means nobody can legally use your work (even if they properly attribute ownership to you) without your authorization.

Copyright law does contain “fair use” provisions which allow use of small portions of a work for certain purposes without obtaining permission, but as a general rule it’s always best to ask permission before using someone else’s work. At least get a legal opinion before using something without permission.