The best setup for autocross on very small tracks

[NoHachi]

I would just use some Koni shocks. Quality is ok and there is a large number of shops in Europe that can provide customer support. If and when you decide to become serious about racing, its a small (yet expensive) step to have them rebuilt to 3 way adjustable, remote reservoir specs. They won't support very high springrates, but you should be fine with a set of 7/4 springs.
The ratio between front spring rate and rear sping rate determines the FRC. Basically it determines what sort of attitude the car has, steady state understeer or oversteer. In a true racing vehicle you want a fair amount of understeer. This ensures that the rear wheels have plenty of grip left for powering out of a corner. The more power you have the more this effect is needed. Rotating the car into the corner now has become much more difficult, that where driver skill comes into play. Rotating the car on throttle and braking inputs should prevent understeer.