If you're asking about how to obtain a copyright, take a look at this article:
http://www.knowthemusicbiz.com/index.php/BIZ-WIKI/Music-Publishing.html
1999.
No. It is my understanding there are some copyright issues.
If you are not the composer of the song then you can NEVER take the copyright as yours; you would have to purchase it from the copyright owners. Also, when the copyright expires, 50 or more years after the author's death (or after publication, depending upon circumstances and national laws) it is no longer copyrighted at all and nobody can possibly own the copyright.
Movie scripts are protected by copyright law. You can purchase scripts from Amazon.com
No you cannot "claim" copyright unless you are the original artist/author. Just because you "found" a copy of something does not mean you own the copyright for it. The only way to obtain copyright is to create it yourself, hire someone to create it for you, inherit it, or purchase the rights from the legal owner.
They are not available since the copyright is zealously protected and the company won't allow them to be made.
For most uses, you would just need to license it from the rightsholder, rather than buy the copyright. Production company information is available on IMDB.
You cannot download Avenue Q. It is protected by copyright and you must purchase it and pay royalties to perform it. You can purchase it from it's publisher, Samuel French.
Nobody can "claim" a copyright of something they did not create themselves, unless they purchase or inherit or otherwise legally receive ownership. Once copyright expires, nobody owns it and the work is "public domain" forever, or until Congress changes the laws to say otherwise.
Sorry, this material by the Philipino author Bienvenido Lumbera is copyright. You will need to purchase the work.
Absolutely not ! That's called copyright theft - and you can be prosecuted for it !
For the most part, you would license your specific use rather than attempting to purchase rights for the entire series. To license a work, contact the copyright holder in writing, explaining your proposed use in detail.