I had a cold the week before my nissen (October 2007). I sucked down more juice, hot herbal lemon tea and water than I ever thought possible - I thought I'd drown in all that liquid. The surgeon said that as long as my chest was clear and as long as there was no fever that the surgery would proceed. Remember to stay away from dairy of any kind - dairy creates mucous and you don't want to produce any extra right now.
After surgery I did not have a nasogastric tube when I woke up from surgery, but I know others did have it. If your doctor puts that in, you'll probably have trouble blowing your nose and your sinuses could be uncomfortable with the tube. Other than that, a head cold shouldn't cause too much of a problem.
In the hospital for the two nights I stayed over, I adjusted the bed so that I was sitting sort of up/reclining and had my knees raised. In this position, I did not build up as much mucous in my chest as people who lay down flat after surgery - it helped keep my lungs clear after the anesthesia (I never had the thing you blow into at the hospital after abdominal surgery to keep lungs clear because the surgeon didn't want me exerting that much effort after the hiatal hernia repair). Sitting up a bit could do the same for you as well as help keep your sinuses clear.
Good luck Monday!