Does the ornish program apply to coronary artery blockage?

Yes. The ornish program of life style changes is certainly a good idea for someone who already had coronary artery blockage. It involves lifestyle changes such as diet, exercise, stopping smoking, and stress management. It is not a replacement for treating your disease with medications where indicated.
Yes. On his website he claims that it reduces bad cholesterol by 40% and lower risk of heart disease. Since high cholesterol is one of the major causes of coronary blockages, reducing it can help with heart disease.