I agree with the first one, in my side by side test, even when using normal maximum toe (+/- 4 in GT4, 0.20 in GT2) the tire that using toe will have less traction on acceleration but more traction in decceleration (tested using +0.20, I think I will test this again using different toe combination). So, using unneutral toe only on rear tire will make the car oversteer, because it will make the rear tire have less traction.
About the second one, I never see any limit in
my test. It seems the physics engine will process any value. Anything that make divide by zero error will result in game crash (this is the reason I use 1 as minimum, 254 as maximum when hybriding). Although using extreme value can give anomaly, but the effect it self seems proportional, extreme value has exagerated effect compare to normal value.