That is standard science. Gravity is a fact. Theories of evolution are different, there have been different theories: Aristotle, Newton, Einstein and soon Quantum Gravity.
The theory is not established. As with all theories, it is the best explanation of the facts we currently have. As and when we discover a fossil rabbit from the Precambrian, the current theory will be replaced.
The watch is designed. According to the ID hypothesis the grass is also designed. Both are designed, albeit by different designers. Hence Paley is incorrect. The difference between the watch and the grass is not a difference between design and non-design, but instead a difference between designer A and designer B. Hence, Paley is useless in distinguishing between design and non-design.