First, set it up like
this. None of the cars in LFS use more than 720° steering, so that is enough. Of course you can force the cars to use more than 720°, but the animation won't match up with your real wheel then.
As for force feedback strength in LFS, it depends a bit on the car. Cars with driven front wheels tend to have lighter FF, so you should set the strength a bit higher for those than for RWD ones. In general I'd say a value around 40% ingame FF strength is good.
It kinda depends on what you like more, though. Setting the strength lower gives you a much wider dynamic range of the force feedback, but small forces around the centre might be very weak or completely lost then. If you set the strength higher, you'll be able to feel those small forces much better, but at the same time the alignment torque forces (front wheels try to point in direction of travel) can very quickly reach the maximum FF strength the wheel can provide, making this part of the FF feel very on/off-ish.
Overall, just experiment and choose what you like best