General:
Race drivers always seek for the duality of physics: He/she wants traction. And Rotation. A good front end and a good rear. The truth is: It's all always there, but what the driver is unhappy with is laptime and corner speed. Always. The Audi has one of the best front ends you can find and it has good electronics, too. But with the big V10 in the back, there's a decent amount of weight that is trying to make your life harder. It provides good traction in quali and allows to slide the rear just about as much as you want. But in the race it will work the rear tires quite a bit and controlling temperature there becomes crucial.

Electronics:
TC1 on 2 or 4 for Q and 3 for the Race feels best for me as the car allows you to actually work with the rear on throttle (The sequence seems to be 1, 2, 4, 5, 3, 6 ... and is mostly down to how much oversteer the TC will tolerate). I would keep TC2 low or off.
ABS on 5 seems predictable

Adjustments (you dont actually need any imo)

• The spring steps are rather large
• stiffen front spring if braking into the corners is an issue or the car is generally too oversteery for you.
• reducing negative toe or going positive on the rear can help this further, but the speed certainly is fastest with negative toe.
• move BB forward if too loose into the corners. 
• adjust rear ride height for over/understeer by 1mm steps.
• Raise the entire car a bit if you want more tolerance in the chicanes, the car barely loses downforce with higher ride heights - however the weight travel will be more pronounced
• For lower rear tire temp you will have to shift the balance further. Lower rear ride height, higher front, stiffer front spring, etc. 

Driving

• into the corners you can be quite aggressive with the brake, the ABS will sort you out. 
• Onto the throttle don't just floor it in the slower corners, give the car some time (say, half a second) and it will thank you
• aim for late apex in hairpins, try to trail deep, immediate but progressive throttle, little to no coasting in tight corners, aggressive throttle in longer corners. early power is very crucial to work the diff and unload the front.
• In the chicanes be gentle with the weight transfer (your front end is better than the rear and will build grip too fast!) and try to live with minimal corrections on throttle and brake to stay on line
• track limits tend to be wide, use it.

LFM:
Fuel already set for 25m and refuel for 45m. Adjust rear ride height +-1mm to your liking. Most likely down by 1mm for high fuel loads.

WARNING:

You will lose tire pressure, make sure to carry enough! You can safely add 5 clicks without having to worry about grip.