Effects panel options for the IK control laye

Question 1

what are the effects for IK while selecting controller and pressing E?

Answer 1

1) IK forearm 2) Goal Hand. (controller is with hand)

Question 2

what are the effects control under IK forearm?

Answer 2

1) clockwise 2) FK 3) stretch

Question 3

What is about Auto stretch checkbox

Answer 3

uncheck it

Question 4

What does Goal hand checkbox for?

Answer 4

whether hand will orient independent (uncheck) or according (checked) to its parent?