You want info for learning? Be careful what you ask for
The course is basically a 4 corner job, there is the first S, but it is easy flat out without scrubbing speed.
Next there is the water splash. On the left, where you approach anyways due to the exit of the S, there is a low spot that I make an effort to keep over. However, you hear the water just like you're running through the center of it, so I question whether the "keep left" is even worth it. Add to that, I don't see a MPH drop through the water, so it seems only for show and audio.
The first real corner is the left hand hairpin. With the WRX, it was easy to get a nice yaw on entry (note I say yaw and not a slide). I'm down to 3rd gear here, with the front end in the grass trying to get a late apex and to the power early. The risk is that this ejects you quickly to the right on exit and in the grass. There are a coupe of small bumps in the grass, but if you ease the car back to the dirt, using the grass pays off.
The next easy left is not a corner, just ease the car in and allow it to move naturally to the right on exit. Here I allow the car to move all the way off the asphalt before easing it into the next real corner.
The next left can be taken 100% flat out and without scrubbing speed, but getting it right is not easy or consistant. My entry point is the patch of green up against the armco. I try to ease the car into the armco while inducing a tiny amount of yaw so that the car does not understeer as the road starts to drop. Often the car enter with a little understeer or in a bit of a slide and scrubs speed. But on laps when you nail it the exit speed over the bridge is awesome.
Entry into the next corner is a bit tough as you are over on the right exiting from corner 2. I ease the car back over and brake on the down ramp and drop the WRX into 4th. Getting good yaw without too much slide while maintaining a good exit speed is tough. I can get consistant after 2-3 laps, but nailing it is tricky.
The last corner, as AOS- suggests, is the key. It is long and tightens on exit. I have tried different lines, especially when trying various cars, but the WRX is the best through here. My current approach is a mid to slightly right entry off the end of the asphalt patch and go deep into the corner, dropping 1 gear to 5th on entry. As the car yaws, I drop another gear and try to keep it from sliding with small brake inputs. The clipping point I try for is the end of the raised bit of dirt on the inside, but often go wide. The exit wall comes up fast, but it is possible to keep the car off it while maintaining speed.
I will try a few slightly altered lines if I get a chance back at the course this week, paying particular attention to the last corner.