Vfrpilot,
The huge tailpipe is to keep the exhaust off the aircraft so it stays all shiny clean
with no black soot on the fuselage. As for turning when the pilot makes a pedal input the pitch is increased on one set of rotor blades and decreased on the other by a mechanical mixing system. The resulting higher torque from one rotor system rotates the helicopter. Also at the same time through the same mixer one rotor disk is tilted forward and the other back helping to turn the aircraft. The only bad part of this system is that at some power settings it is ineffective. This in turn can cause some interesting moments for an inexperienced pilot. I remember the first time it happened to me. As I was approaching to land the nose started wandering off to the left so I added right pedal and added and added right pedal until I hit the pedal stop and we were still turing left! About this time the other pilot flying with me told me just to add a little collective and the proble would correct itself. Sure enough it did but it was still one of the more interesting moments of my training!
Brian