I use a hovabator, chicken egg incubator, for my eggs. but I do not regulate humidity with the incubator. I place my eggs in a container ,(large ziplock container)with my desire substrate and put 1 very small hole in the lid for air exchange. I then keep the moisture in the container and regulate the container of substrate, not the incubator. As long as the incubator stays at my desired tempature, and i keep my substrate moist, all should be fine. I usually check my moisture/humidity levels about once a week.
A fan, as long as it doesn't blow extremly hard or on the containers should be fine.