The restaurant sector is on watch after a pre-earnings warning from Darden Restaurants (DRI) and a harsh downgrade on Wendy's (WEN) sets a negative tone. The picture being painted for 2013 is starting to get pretty consistent - margin pain and soft traffic trends. Other things to watch in 2013 for the sector: 1) The impact of higher payroll taxes. 2) The coming costs of the Affordable Care Act. 3) The push to raise the minimum wage. 4) Which chains can succeed in China and India?