If this is zero, then the execute context time will be used. If this is positive then it will override the delta time. A negative value will prevent the solver from stepping, but there will still be update costs associated with the node.
If this is zero, then the simulation delta time will be used for evaluating movement of the simulation space. If this is positive then it will override. This may be needed if the component movement is being done in parallel, in which case you might need to pass in the previous time delta here.
How much of the simulation is combined with the input bone. This currently happens in component space. Note that the simulation will continue to run, even if alpha = 0