Everything written or recorded since 1923 is affected by copyright laws.
You would want to protect it by copyright, not patent. Copyright protection is automatic as soon as the music is fixed in a tangible medium (notated or recorded).
Your music would be protected by copyright as soon as it was written down or recorded, and a publisher is not immediately necessary. You may wish to become a member of a performing rights society, however.
Copyright is a complex legal issue especially with the numerous amendments etc. Basically it is free of copyright BUT recordings would have copyright as would the printed music, that is, the music publisher would have copyright on his production of the printed score. An example is and please do not take this as binding legal advice - you decide to put on Carmen in your town hall so you photocopy the various parts of the score - your photocopying most likely breaches copyright. As I said its complex.
You would need to go directly to the rightsholders individually.
The music of ABBA is protected by copyright laws and it would be illegal to post sheet music.
Radio affected the world by having all these different kinds of music coming together as one such as R&B, Rap, Techno, Jazz, Hip hop, Rock and roll etc. I would say it was unusual for most people but it affected everyone and got people into music. It was the most popular thing in the world. Everyone started to dance to it or sing along with the songs that played on the radio. That's how it affected the world.
You would need to go to the publishers individually; there is no clearinghouse.
be sued in court for copyright infringement
First, you do not need to apply for a copyright unless you plan to enforce it; your songs were copyrighted automatically the moment they were written on paper. The "music", if any, would have its own copyright once it is composed and recorded, whether it is put onto paper or not. In fact, each new sound recording of a new performance of the music is a slightly different "creation" and would have its own "sound recording" copyright, which is owned by the performers or producer.
Without permission, yes it would be an infringement of the artists right to control distribution of his/her music.
kinds of thai music 1. ritual music 2.entertainment music
There is no preset fee structure. You would have to locate the copyright holder first. Then you would need to negotiate a license to use the material.