A ton of cancer is caused by free will if you consider the choices people make. Smoking is a biggie. The chemicals in the environment that got there due to human industry are another. The rate of cancers would be much, much lower without many of the human interventions that have occurred. This is not to say that these things are "bad" but you can't deny the causation factors. Cancer is a pretty poor argument. Sure there is some random smiting, but many many cancers are unfortunately absolutely traceable to human factors (without a moral agenda - just being their industrial, creative or needy little selves).
Tsunamis and Earthquakes have been happening forever - that's a part of how the Earth works. It's nothing to do with the people on it or the Creator.
My discernment between Faith and Superstition probably won't work for you. (Linnea and/or Ben may want to answer this question as well, I'd be interested in their response.) To me, superstitions like, say, avoiding walking under ladders or breaking mirrors have no bearing on my life or experience. Those 'beliefs' are meaningless in the context of my whole life. However, my abiding belief in a loving God who has purchased redemption from sin and death by sending his Son to die for the sins of the world is real; it has demonstrated real transformative power in my life and the life of others; and prayer has demonstrated real results in my life.
You may be able to try to argue that the effects of my faith in my life are psychological and not real manifestations of some power working in, around and through me - but you know, it doesn't really matter to me because it is working for me and my life, and that of my family and children, and that of my friends in the church, and that number of people with positive, real energy working in the community is so powerful and such a mechanism of good that really, there is no reason to argue at all. The results speak for themselves.