The neck works with the traps to help to keep the shoulder girdle stable during the lift. That's why the neck is flexed and tight. Try lowering the head, chin resting on the upper chest, and pulling to the top of the forehead/head if that tightness really bothers you. You will get another angle to the exercise and less neck strain.
Crunching noise may be the bone/wrist placement being somewhat tight at the beginning. If not pain, than probably just need a warmup in the area. If doing wrist curls correctly, than you should have the bar extend all the way down to the finger tips. Helps to develop the full function of the grip and exercise. I'm talking BB wrist curls here. Reverse BB wrist curls also work well for the forearms. As do false grip (thumbless) reverse BB curls. Good Luck.