In the reaction below how would adding more of product C affect the equilibrium of the system? A+B arrows both ways C+D

In the endothermic reaction below how would adding hear affect the equilibrium of the system? A+B + energy arrows both ways +D

In the following reaction, if you wanted to produce more hydrochloric acid (HCl2), what would you do? 4HCl + O2 arrows both ways 2H2O + Cl2