Thanks John. I appreciate all the answers here and I got alot of helpfull information here. There are still questions of the US copyright (Library of congress) which after reading more, now confuse me. Reading more on this forum and other forums gets me with more diverse answers. For the benefit of myself, and I believe others, I will write them down and hope a laywer in this forum would be kind to help answering them and remove any doubts:
Can it be clearified if works (music, text,...) with no connection to each other of the same author can be registered all together for the cost of 1 form filling (35$ right now) ?
Practically, what does it mean a collection and why do I need to know about it ?
My work was published on Soundcloud, only about 200 people have heard it and there was only 1 download. I wish to register it. Is it considered published or unpublished work ?
A work is published on the internet (like www.SoundCloud.com) of a foreign autor from a PC located outside of USA. does US court regards it as a published or unpublished work ?
Suppose I have published a work a year ago. Can I register it on a form of unpublished work ? what is the benefit of registering my work on a published work filling form ?
After I fill the registration I cannot delete any data, so I must be sure-how can I register in a way that my personal details (address, phone number) won't be available to the public, but will be available only to the US Copywrite office? Can you please show the forms and mark the places in the forms where any details I fill will be private and available only to the library of congress ?
Can Common creative license of a work be changed to "all rights reserved" after it was published ?