You can post someone else's content but give them credit and link back to the original article and they will love you for it. This is actually happening a lot right now.
This is incorrect. In theory this would work because it sounds like the right thing to do and the copyright owner would appreciate the reciprical link and credit.
Unfortunately, it doesn't work this way with copyright law. You can quote bits and pieces ( or linking ) by referencing the author but copy and pasting the whole article is illegal without direct consent from the copyright owner.
About a month ago, I faced a similar situation when we pasted a particular news article on our site. Proper credit was given including the name of author and copyright date. I can only assume it was "google" that brought the copyright owner to our site. She gave us a choice of cease and desist or fee.
We choose to take her material off our site.
Copyright law is serious business. The search engines make it that much easier for rightful owners to protect/monitor their work from potential infringers. Copyright theft can cost up to $150,000 per infringement.
I am also aware of a couple websites that have violated our trademarks and copyright. We sent cease and desist letters with
screenshots of the offending material. We then wait...the longer they violate the more they will have to pay down the road.
I hope this helps.