I received a message from Tom Burkland regarding the alignment options on the TFA lakester and Tom mentioned that on a FWD car large amounts of caster maybe is not a good idea. Caster increases the trail of the suspension in side view, which means the tire, which is pushing forward, has a longer lever arm to try to disrupt the direction that it is pointed when deflected by an outside force, like a bump or a driver correction. As the caster is decreased the lever arm is shortened and the steering should become more stable but this also means that the steering mechanism should be very stiff i.e. minimum deflection related to applied load, so such things as the steering links from the steering box to the wheels should be large diameter and the steering arms should be stiff and the rod ends should probably be larger and probably should be in double shear on both ends and the mounting of the steering box itself should be very stiff.
Imagine a caster style wheel, like the kind on one end of your tool box, it is allowed to pivot around a vertical axis which allows you to "steer" your box around the shop, this works pretty well because the caster wheel has lots of "trail" (the offset between the wheel axle and the vertical "steering" axis) and the force that the wheel applies to the vertical axis is behind the axis and is in the opposite direction of movement. So now imagine if you could now apply a drive torque to the wheel so it is trying to push forward on vertical axis, as soon as there is any misalignment of the wheel (now driving forward) with the centerline of vertical axis, the wheel will want to drive around the vertical axis, which means it is no longer pointed forward. This argument probably could mean that using zero or possible some negative caster may be the most stable under power . This configuration could possibly have a stability problem at trailing or no throttle conditions because of the lack of positive caster. I think I would really consider a good steering dampener.
Regarding toe in or out for driven wheels it is probably very dependent on the scrub radius. If the scrub radius is positive (a line through the steering axis falls outside the center line of the tire patch) as drive force is applied the wheel wants to turn outward increasing toe out which would indicate that a static toe in alignment would be desirable. If the scrub radius was exactly on the center of the tire patch there should be no increase or decrease of toe due to the drive force, and obviously if the scrub radius is negative the drive force will cause a torque about the steering axis to increase toe in. All this being said I believe that any toe out on a driving wheel (front wheel drive or rear wheel drive) is not desirable and can cause direction instability, so my recommendation is to always align the wheels with toe in. The amount would be very dependent on the stiffness of the steering system to reduce deflection due to drive wheel torque inputs around the steering axis.
Rex