SAN Air Carrier departure reported multiple confused clearances issued by the controller that led to a go around and take off cancellations.

Narrative

We were waiting for take off on Runway 27. The Company flight ahead of us was given; 'Line up and wait; traffic crossing down field; landing traffic six-mile final.' After they took position; they were cleared for take off. Shortly thereafter; their take off clearance was canceled because of traffic crossing down field. They were reissued a take off clearance; and we were given; 'Line up and wait; traffic four-mile final.' As we finished lining up; the Tower Controller excitedly said something about C2 to the North; and did not wait for a response. The Controller asked another carrier to move up to allow room because he was blocking C2. We queried if we were cleared for take off or not; and the controller said no; to clear the runway to the North on C2. As we were clearing; the controller sent the traffic on final around. The other carrier was then cleared for take off and then us. Both the First Officer and I decided that the Tower Controller was talking way too fast; and was difficult to understand. If this was Controller training in progress; the Supervisor let her go too far without intervening. If this was a current Controller; he/she needed to take a break. In less than four minutes the controller cleared a flight to take off with traffic on the runway; abort; re-take off; us to lineup and wait; clear the runway; and a go-around on final.