Stocks Set to Open Up; Grey in Spotlight  NEW YORK (Reuters) - Wall Street was set to open higher on  Monday, with advertising group Grey Global &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=GREY.O target=/stocks/quickinfo/fullquote"&gt;GREY.O&lt;/A&gt; in the  spotlight after a UK rival agreed to a \$1.31 billion deal to  buy the company, while investors will be eyeing higher oil  prices and awaiting economic releases later in the week.