Ok, i'll give all three a shot :)
first, the LSD. A differential is intended to allow power to the wheels. However, under cornering, one wheel must turn faster, while the other must turn slower (try pushing a wheelie bin around a sharp corner, and watch the wheels, you'll see what I mean). However, to cut costs and weight, many manufacturers put an 'Open' differential into a vehicle. Simply put, when enough power is put down, the wheel with the least traction begins to spin, as in doing a burnout. In differential terms, this is called Slip. A Limited Slip Differential is exactly that, it limits how much slip occurs between the two wheels. The wheel with the most traction ends up getting the most torque, this type of diff is really good for street use. Just dont put one into a front-wheel drive car, cos that makes it a pig to drive..
VCT - Variable Cam Timing. IIRC the Falcon Six's VCT setup retards the cam timing by 10 degrees after the engine revs exceed 4000rpm. From my understanding of it, what happens is that when the engine revs exceed 4000rpm, the engine retards the camshaft timing 10 degrees in relation to the crankshaft position, which allows a better higher RPM cylinder fill. Unfortunately, it also retards the exhaust timing, being the Falcon's head is still an SOHC design. This feature should be better when the Falcon comes out with a DOHC head.
IRS.. The AU Falcon uses one of the very best IRS designs featured on a sub $50,000 mass-produced car. To use one scenario of IRS in use, imagine you hit a pothole going through a corner, with one of your rear wheels. If it were with a live rear axle, the other wheel must move proportionately to the wheel that hit the hole. This will affect your car's handling, since if one wheel dips a few centimetres, then the tyre on the wheel on the other side of the vehicle must change its camber to accomodate the other wheel's movement. With IRS, each wheel is able to act independantly of each other, so even if one wheel does hit a pothole mid-corner, chances are the vehicle will not be adversely affected by that one wheel's movement.
hope this helps!