What are the rules/practices for byline? If I have paid for the article and own it?

Depends upon the terms of the agreement you had with the author.

What ccDan said. If it's actual ghostwriting, it would be normal for you to put your name on it as the author. But simply buying an article from a paid writer doesn't automatically make it ghostwriting. The terms need to be spelled out in the agreement. BTW, if you don't have either a written agreement stating the article is a work for hire, or a written agreement signed by the author transferring copyright to you, the author still holds the copyright, even if you've paid to use the article. So, especially if you plan to use it more than once, it's very important to get those terms in writing.

Beagle...thank you for the insight.

Much appreciated.

I've met some webmasters who seem to think that by giving a by-line they are somehow losing something. When I visit a website I'd far rather see articles by different authors than lots of articles with no name. By-lines don't cost anything and are a sign of respect applied to well-written work.

Don't forget that many academic and government sites love listing their sources but hate to write 'Unknown Author, www.widgets.foo/page.html'

"After having an article written by a hired author, do you display the article on your site AND submit to article sites?"

If you will display the article on your site, don't submit it to article sites to avoid duplicate content penalty.

Why no just leave it off your site, submit it to the article directories with a link included to your site and let others worry about dup content? One way links are golden.