Harrah's, Caesars: FTC Asks for More Info  SAN FRANCISCO (Reuters) - Federal regulators have asked for  more information about casino operator Harrah's Entertainment  Inc.'s &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=HET.N target=/stocks/quickinfo/fullquote"&gt;HET.N&lt;/A&gt; proposed \$5 billion acquisition of Caesars  Entertainment Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=CZR.N target=/stocks/quickinfo/fullquote"&gt;CZR.N&lt;/A&gt;, the two companies said on Friday.