A:
Hi. Eco cycle is a cycle that is designed to use the least amount of water and energy as possible. The downside is that it can take up to eight hours of run time. The use, per the manufacturer, is where you start it and go to bed. And your dishes are ready for you in the morning. I can say that we have never had ours run that long. We have used the cycle when doing very lightly soiled dishes, etc. and it has worked well.
On the question of heat drying, yes, you can turn that option off. There is also an eco cycle for that as well, which takes less energy but doesn't dry as well. Hope this helps!