questions on a chemistry experiment

I'm not sure how many of you know about the copper + nitric acid experiment, but basically, you put boil several samples of acids (namely hydrochloric, sulfuric, nitric, and phosphoric), and then add copper to each sample. The copper is only supposed to react with nitric acid at a significantly level since nitric acid is a strong oxidizing agent, while the others are fairly weak.

Q1: why do you need to boil the acids?
Q2: does anyone know if the concentration will affect the results? I'm planning on using the same molarity for each solution.
Q3: what kind of indicator would be good to use if I were to use 1M of each acid? I want to show that the pH of nitric acid and sulfuric acid increased after it reacted with the copper.