Crediting quotes, or other copied copyrighted material, can still be infringement under U.S. law. Proper attribution of the material copied does not change an infringing use into a fair use.
Also, it does not matter, always, how much materal you copy, as small amounts of copyrighted material copied can be infringement if you copy a vital part of the material.
Even if your site is a news site, you are still governed by copyright laws. For instance, you may take material, the facts, from an AP release, but you cannot copy the release verbatim without violating copyright law. You cannot quote a paragraph of a news article, even with attribution, without permission from the writer or the news organization who owns the work. You cannot use quotes gathered by, say, a reporter interviewing a witness, without verifying that the quote is accurate, and then obtaining permission from the witness to use it.
You cannot link without permission.
Ideas and facts, however, are never protected by copyright and can be used freely. What is protected is the manner of expression - such as a writer's analysis of the facts or event, the way the writer has structured the material to present these facts, which facts were used and how, and the choice of words used to present these facts.
You could get into trouble using the copyrighted work of others if you do not alter it and make it original. Merely copying someone else's presentations and putting quotes around it will get you in trouble. I cannot, in other words, quote portions of Mitch Albom's story in my own story without violating his rights and the rights of the Detroit Free Press by doing so.
In other words, even when your use of the material is "newsworthy" it will not protect you from an infringement suit.
It is best to seek permission from the owner of any copyrighted material.