I'll answer those two questions:
How do you avoid hitting the wall after drifting?
It depends on your drift [your angle when you tackle the corner]. If you're going too fast through a corner and you don't have enough traction, you're going to hit the wall. Of course, if you go through a corner by balancing between the throttle/braking to maintain the drifting line, then you won't hit the wall. Usually on my lo-speed drifts, I go 40-45 MPH. In my medium speed drifts, I go around 60 MPH and in my high speed drifts I go around 80-90 MPH.
Do you just take the drift early?
Try feint drifting. Here's how you feint drift:
Imagine a right corner coming up in 5 seconds. You're going 150 MPH in a Nissan Skyline. Here's what you do:
1. Stay on the left hand side of the road.
2. When the turn is about to come, turn slight ly to the right like you're going to scrape the right wall.
3. Then, turn left and brake hard, so that the car starts to loose traction.
4. Turn right and brake.
By now, you should be going through the turn. Let the car roll until you think that you need to start countersteering and have more wheel spin.
5. Countersteer and adjust the gas pedal as needed until you clear the corner.
KEY NOTE: BETWEEN STEPS 3 AND 4, LEAVE A SPLIT SECOND OF LETTING THE CAR ROLL. IF YOU ARE USING THE DS2, LEAVE THE CONTROLS ALONE AFTER STEP 3 AND THEN START TO CONTINUE TO STEP 4.
This was done on the first right-hander of Tokyo R246
I'll post some pictures of what I mean if I can do it tomorrow