It's a pretty common misconception, I'm not sure how it started, maybe it used to be true somewhere? But no there are no restrictions on hunting porcupines as long as you have a small game license. As for where to find them, look up... I've seen them in both coniferous and hardwood trees, usually thick forest. In the early spring I've sometimes seen them walking around in open fields eating grass, they must be starved for greenery at that time of year and grass comes out before leaves?