The viscous coupling is just as it sounds. It uses fluid to transfer power to the front. Kind of like a torque converter. The only difference is that the fluid would thicken as temperature increases when there is slipping between the two turbines. In cold weather, this almost doesn't thicken. 5% of the torque is only about 15 ft lbs at peak. Even at the full 40%, your talking 100 ft lbs.

What kind of tires are you using? That plays a much bigger part than any electronic nanny or awesome drive train you have. If you don't have snow tires on, your not going anywhere.

Subaru AWD uses a transfer case. Very much like a normal differential. It's actually very backwards like a truck. With that said, it's a lot more "useful" in getting you going in the snow. WRX and EVO just added clutch packs to the diffs and use electronics to control the engagement. The 4WD in the P-cars are not designed for this purpose. It's to assist in cornering. That's why they drive like a RWD car. The 997 C4S is actually quicker around the track than a CS. They do share the same AWD system with the 996.

The 997 turbos does change this to a system similar to the WRX and EVO which allows the engineers to control things electronically.

There is nothing wrong with your system. Get some good snow tires. Narrower the better. You'll be able to get around.