So caching results for steps with the same arguments is trivial. Ultimately I would say you can combine the task-based pipeline with a function-based pipeline to achieve such dynamic control as you specified in the first two scenarios.

About the third scenario I'm not sure. If the configuration has changed, shouldn't the relevant steps (the ones where the configuration changed and their dependent steps) be rerun?

At any case, I think if you stay away from the decorators, at the cost of a bit more coding, you can achieve your wishes.