What are the copyrights risks I am facing here? Will they eventually ask me to take out the articles, or they will sue me and fine me? Who owns the copyright? the directory, or the writer?
A basic and commonly used copyright notice is: (c) year - writer/company name. All rights reserved, Used by permission only.
All rights reserved means they're the owners and hold all rights to control it's distribution. The date is when it originated and the time period.
The key phrase there is:
"permission only"
This means if you want to republish the document - ask 1st and detail what your intentions of use are.
The copyright owner will base their decision on:
A) if you are re-publishing their document for "free use" with no charges attached to view the document. In this case, they'd most likely have no problem with this, and state that you also clearly publish their (c) copyright notice at the end of the article, with a link to its origination.
B) if you are planning to charge people (in a private members area, or resell outright) to view or download their document. In this case, they'd want to write a contract with you and set up a royalty rate in which you'd have to pay them for each individual sale (or a flat one time fee or both).
They also have the right to refuse any duplication for any reason they want.
ezinearticles.com and places like that
Took a quick look at that site. They did a pretty good job covering their terms. For both authors submitting to their site and other publishers wanting to republish their materials.
EzineArticles.com Terms of Service For Authors
Terms of Service For Publishers Who Wish To Reprint Any Content From EzineArticles.com
And if for some reason you don't want to go with the steps above (which would be good because they'd respect your ethics and you may end up having a long term partnership developing with them) , if you just post it, as phillian pointed out, then they'd contact you to take it down or modify it to reflect it's origin and copyright notice.
If you're passing it off as your article (when it's an exact duplicate), or your copyright and reselling it. That's copyright infringement and looking for major trouble.
Good luck!