Adding a catalyst to a reaction at equilibrium

What happens to a reaction at equilibrium if a catalyst is added to it?

Which of the following statements regarding catalyst is not true? A catalyst remains unchanged in composition and quantity at the end of the reaction, A catalyst can initiate a reaction, A catalyst does not alter the equilibrium in a reversible reaction, Catalysts are sometimes very specific in respect of reaction

(i) What is the effect of adding a catalyst to a reversible reaction? (ii) What is the effect of adding an inert gas to a reversible reaction? (iii) How does temperature change affect a reversible reaction?

(i) What is the effect of adding a catalyst to a reversible reaction? (ii) What is the effect of adding an inert gas to a reversible reaction? (iii) How does temperature change affect a reversible reaction?