The IC sprayer is like a washer sprayer. The cooling effect works off of evaporation... so just watering down the IC wouldn't do anything... it has to be a small enough amount of water so that it will evaporate. As for the DCCD... this is from a SOA technology document...

Driver Controlled Center Differential (DCCD) All-Wheel Drive
Impreza WRX STi is equipped with the brand’s most performance-directed All-Wheel Drive system, called Driver Controlled Center Differential (DCCD).

In the latest DCCD system, an intelligent automatic mode actively adjusts power distribution through the center differential to suit road and driving conditions. (The DCCD name itself goes back to earlier systems offered in other markets that provided only a manual mode.) Manual mode in the current system allows the driver to vary the power distribution to suit specific performance demands.

A planetary center differential provides a performance-oriented 35 percent front / 65 percent rear power split. In Automatic mode, the electronically managed continuously variable transfer clutch can vary the split ratio as needed to suit driving and road-surface conditions. The transfer clutch will vary the center differential power distribution ratio according to throttle opening, cornering force (lateral g), acceleration and deceleration (longitudinal g) and wheelslip.

The transfer clutch uses a pilot clutch, which allows the system to use a small, light electromagnetic main clutch. There’s no need to establish hydraulic pressure, eliminating a need for pumps, pipes, valves and an actuator.

Automatic mode provides the best all-around performance for most drivers and driving conditions, varying the front/rear torque split automatically depending on driving conditions and driver input. The system responds to acceleration, deceleration, cornering force and wheel slippage to determine the ideal power distribution.

Taking A Curve With DCCD
As the driver releases the throttle and applies the brakes approaching a turn, the center differential locking force is minimal. As the driver turns the car into the apex of the curve, the lateral g force increases. As a result, DCCD begins to lock the differential, transferring power to the front wheels. As the car exits the corner and the driver applies the throttle, DCCD continues to progressively lock the differential to help prevent oversteer and maintain stability.

Manual Mode for Special Driving Conditions
In Manual mode, DCCD allows the driver to vary the front-to-rear torque distribution to custom tailor All-Wheel Drive performance to specific driving conditions. The driver first selects Manual mode with a console-mounted button and then turns a thumbwheel on the center console to select from among six levels of center differential locking. Increasing the lock factor keeps more power at the front wheels, which the driver might want to do in certain driving conditions, on specific road surfaces – or to suit a personal driving style. Locking the center differential essentially renders a 50/50 power split with no differential action, therefore making this setting suitable mainly for slippery road surfaces that will allow some wheel slippage.