You’ll need black and white yarn for sure, you can choose the color of the iris of the eye and the main part of the beanie.

Gauge is not super important, use the size hook you use most commonly for your beanies. I use the bigger K hook to make a slouchier beanie, and the J hook to make a more fitted one, but that’s based on my gauge and tension in my own stitches. It might be different for you.