Not in the US, Copyright laws are Federal Laws. States cannot change the Federal law.
Other countries have different laws, but most are very similar and based on international agreements.
A little, but members of the World Trade Organization have to comply with the rules of the Berne Convention, which means they're all using the same basic framework. Berne requires protection for a minimum of the life of the author plus 50 years, but some countries (such as the US) have increased this to 70 years. Berne also asserts that materials must be protected as soon as they are fixed, but some counties (again, such as the US) have optional formal registration that allows for certain additional awards in court.
They briefly did in the 19th century, but federalized copyright eases interstate trade.
State copyright laws also continue to protect "sound recordings" made prior to February 15, 1972, which have no federal copyright whatsoever.
Most state copyright laws have been pre-empted by federal laws.
Each state does, however, have its own copyright laws regarding sound recordings made prior to 1972.
No; state law covered sound recordings for many years, which makes reissuing records very difficult, but current copyright law is federal.
Yes, each state has copyright laws regarding sound recordings made prior to 1972 and a few other things that are not preempted by federal copyright laws.
Each book has its own copyright information.
Each program has its own copyright information.
Each song has its own copyright year.
The year of the encyclopedia is the year of the copyright; there are far too many editions to answer this question directly.
Each volume has its own copyright date.
Each issue or edition has its own copyright information.
Each of the 15 editions has its own copyright year.
Each issue would have its own copyright information; the first issue would be 2002.
A company doesn't have a single copyright date; each copyrightable work it produces would have its own date.
Yes; there is no minimum age for copyright protection.
Warner Chappell administers copyright of the song itself, but each performance and recording will have its own additional copyrights.
The song itself is controlled by Music of the West, a division of Songwriters Guild of America. Each recording may have its own copyright.