FlightXML2 does not currently expose estimated departure time, which is what I suspect you would like to see. A future version of our API is planned to do this, however.
For now, you can compute an approximated estimated departure time by computing the result of: (estimated_arrivaltime - filed_ete).
When a flight is cancelled, the actualarrivaltime and actualdeparturetime will be -1
When a flight is diverted, the new ETA may be available through the estimatedarrivaltime, but that is subject to being incorrect since many things occurring during a diversion are unusual and atypical so ATC infrequently does not properly update all aspects of the flight plan.