Experience stacking and fishing

Hi, Some more questions. I also wanted to thank those who responded to my first question. My next two questions:
1. Does the premium experience boost with the experience potions in the game? For example, I believe the premium service experience boost is 20% ? If I purchase a potion with an experience boost of 20% will this raise my total experience boost to 40%?
2. I learned fishing is a good way to make gold. Is there a special quest I need to complete in order to start fishing or can I just purchase the items needed and if so, where would I purchase the correct items?

Thanks again!