Regarding cast-iron pans, I have found that it is best to keep my iron pans only for cooking that will not reduce the finish, such as frying. The bane of cast-iron (apart from soap) is the tomato or anything acidic, so do not cook tomato sauce or tomato-based curries in it. I also find that milk products tend to reduce the finish.
I keep a separate stainless steel sauté pan for cooking things that are not cast-iron friendly.