Yes, copyright is a "property right" that can be simultaneously owned by multiple people, either as joint owners or as "tenants in common" ownership of some percentage.
Songwriting copyright, or publishing rights, is the aspect of song protection separate from the performance or recording; it is right in the underlying work.
People who have broken copyright law are called infringers.
Two people in separate households can have the same insurance policy. Usually, you can give the insurance company separate garaging addresses.
The Copyright Act, the Counterfeit Goods Act, and the Trademarks Act are three separate acts of South African legislation.
People cannot be protected by copyright.
Same as copyright notice for anything else: Copyright, or copr. or circle-C, the date of copyright and the author or other copyright owner's name. E.g., "Copyright 2012 Walt Disney Productions, Inc."
A copyright notice may be in the file's properties, in a separate "read me" or "about" file, or embedded in metadata. Notification is not required for protection.
No, all are separate people in the Bible.
Not necessarily. The release date can be well after the copyright date.
Copyright protects music and lyrics (sometimes separately, sometimes together) and recordings (separate from the underlying work). The copyright holder has the exclusive right to copy, alter, distribute, or perform/display the work, or authorize others to do so.
Not always. A popular book may come out in many editions over many years, but the copyright date stays the same.
Ir isn't necessary unless you feel there might be a need to separate them for financial reasons (selling to two different entities). In all likelihood you could register them as a collection with the copyright office.