1) Most important thing is, how does he feel now; any recent chest pains?, any shortness of breath? If no, but you want to be very careful, asses his cardiac performance- stress ECHO or stress perfusion tests - dobutamine or persantine. But if he doesn't have first 2 signs, and no arrythmias on plain EKG, I would not bother with major cardiology assessment. Remember- presence of chest pains, shortness of breath and arrythmia are most important from his history ( see Goldman criteria) to asses his risks for perioperative cardiac complications, and not the fact that he had CABG, which is a protective factor - they were supposed to fix his coronaries - which I hope they did.
2) Laparoscopic cholecyctectomy is a " minimally invasive operation", and as long as he can sign his check without getting angina, he will do well. ( joke )
3) To make you feel even more relaxed, we do lap. chle. on patiens, who had CABG every day.