It depends what side of the equation you're on (owner/user), the amount used, the purpose of the use, and more. In most cases, permission in writing needs to happen, but this is not always the case.
A) Use only original material B) Use only material confirmed to be in the public domain C) Find the copyright holder of any other material and, in writing, obtain the necessary permissions.
The copyright holder, or anyone the copyright holder authorizes.
No. Unless things have changed, the most accepted form of not breaking copyright with printed material is that up to 1 third of the material may be copied for reference purposes. Any more then that is breach of copyright. Why do you think it's called "Copyright" if any one is allowed to copy it entirely? The "right" to copy it remains with the copyright holder.
You would need permission from the creator or rightsholder to use any material that is not your own.
No. Public domain means that the material is available for use by anyone, without copyright restriction.
You may use copyright protected material when you are the copyright holder, or when you have permission from the rightsholder or an exemption in the law. The most notable exemption is fair use or fair dealing, which allows certain limited unlicensed uses in situations such as education and commentary.
Contact the site owner by looking them up in whois.
Contact the copyright holder and request permission.
Infringement is the use, without permission, of copyrighted material that does not fall under a "fair use" or other exception to copyright law,
You would be guilty of copyright infringement, a federal crime.
Unless it would fall under "fair use" no it is not "okay" to use copyrighted material without permission
You will find that most material on websites is protected under copyright. The website owner should be able to tell you who the copyright owner is. You would then negotiate a price with the copyright owner to allow you to use their material.