How will the equilibrium: Heat energy + CH4 + 2H2S = CS2 + 4H2 be affected by the following?

a) A decrease in temperature?
b) The addition of H2
c) The removal of some CH4
d) An increase in the volume of the container
e) The addiotion of a catalyst.

i know that [CH4] goes up
[H2S] goes up
[CS2]goes down
and [H2] goes down.

e) is no change.

But why do these shift? that's where i am confused.