sorry but i dont know the difference becuse we use original pistons.
I am sorry, but at a high speed track like that a softer setup should fit very well. Red springs may be to hard. U have to try some.
The oil gets hot and it gets easier for the pistons to move. The springs is that makes the ride hight, yes but some millimeters lower becuse of oil temp.

But depends how long you run. 10 minutes make almost no difference.