The getPosition command in the Maestro library will return the current target position the Maestro is sending to the specified channel, so that might also help you determine where your script was stopped. Also, it might help you to know that if a movement command like 6000 0 servo is executed in a script and then the script is stopped immediately, the Maestro will continue commanding the servo to move toward this target.
To change the length of time to wait for a movement to occur for a frame in a sequence, simply double click the frame in the "Frames" portion of the "Sequence" tab, and type in a new duration in the dialog box that appears. However, you should know that this does not affect the movement speed of the servo, only the length of time the Maestro waits before beginning the next action.
For more information on how the Maestro controls servo speed, you can look at the Speed and Acceleration headings under the Channel Settings section of the Maestro user's guide. To learn how to change the speeds on a channel as the program runs, you can look at the Set Speed and Set Acceleration headings under the Serial Servo Commands section or the Servo, LED, and other output commands table of the Command Reference section of the same user's guide.
Finally, please note that there is some physical speed limit on the servos themselves as well and even if the Maestro is sending a faster move command, the servo will still be limited by this physical limit.