A few of the Paul Newman dressings are under the 2 carb a serving rule.

You can have cheese just make sure it is only 3-4 oz daily and those bags of salad are still very low in carbs so I wouldn't worry. Just stick to the mandatory 2-3 cups daily of veggies and you should be fine.

If you go over a carb or two with veggies it is fine and always remember to subtract the fiber from your carb total.