What are the elements of a closed loop planning, monitoring and controlling project management system? What is the foundation of any system? What are the common issues associated with implementing a disciplined PM System?

1) What are the elements of a closed loop planning, monitoring and controlling project management system? What is the foundation of any system? What are the common issues associated with implementing a disciplined PM System?
2) Can you discuss the changes in CPM forward and backward pass between planning and monitoring a schedule? What are the influences of time-now? How do original and remaining durations differ from each other?
3) What are some of the basic techniques used to measure performance in terms of scope and schedule? Is it possible to schedule without scope? Why or why not?