dameetz: They are about +5deg in the middle.

Cain:
DRRS however you prefer the feel
Lower will feel softer in punch, but will allow faster gear.

Advance however you prefer the feel, and in direct conjunction with gearing for temps
Lower will feel softer in punch, but will allow faster gear.

On a low traction surface for 2wd, I personally the DRRS around 5-6, and the advance around 4-7 depending on exactly how slick it is. Then I gear for best laptimes.

On a high grip track, I like DRRS around 7-8, and then play around with both gearing and advance to give me the feel I want with the best laptimes.