A set of letters or numbers on the copyright page generally refers to the number of the printing or edition of the book.
With the permission of the copyright holder.
Assuming you have a license from the copyright holder to print the song in your book, you would hold the rights for the book as a compilation.
Once you have written a book, it is copyright to you. All writers copyright their own books.
Not necessarily. You need to make sure the copyright on the book has expired.
The letters are Roman numerals that stand for the number (hence the copyright year) 1950.
Usually the page in small print before the title page.
No, you can't as the book is still under copyright and print.
Contact the copyright holder or print rights administrator.
"Out of print" does not equal public domain. A work is safe to use only if the copyright has expired or deliberately been placed in the public domain by the rights holder. Or if the copyright has expired and was not properly renewed.
Certainly you can, but any reproduction of a document still under copyright is a violation of copyright law, whether or not it is in print. For works copyrighted after 1963, copyrights run for a minimum of 95 years. Be careful.
The national library of the country in which the book was published likely has information on file.
if you retained the copyright, yes you can republish it. or if it became public domain then it could be republished.