Transit visa in China Beijing Airport

Leaned on the news that start from 01 Jan. 2013 visitors from 30 listed countries are allowed to stop over free in Beijing for 72 hrs. I am a Canadian, on above said country list. I am scheduled to arrive Beijing Airport on 30 March 2013 at 4pm, stay approx. 48 hrs and depart from Tianjin on cruise ship on 01 April at 5 pm. Do we need tourist L in advance?
Furthermore, the ship will dock in Shanghai few days later after visited Japan, Korea for 10 hour. Do we need another transit or tourist visa?

Could the airline (UA) refuse us board the plane to Beijing if we do not have visa in advance?

Matthew & Mimi Kong

Matthew Kong