http://www.motortrend.com/cars/2009/...ons/index.html
The SE only comes in 4 Cylinder.
The VVTI is variable Valve Timing. It helps to increase Torque and Horsepower across the powerband depending on RPM's etc. It actually changes the Valve timing.
The 16 valve comes from the fact that it's a twin cam design so it's got 4 valves per cylinder.
There's no "advantage" per say over the V-6 other than better Gas Mileage. The V-6 will have VVTI and 24 Valves.
Same thing as your current Engine with 2 more cylinders.