Reply to Anyone in the navy?

I was curious as to how many people who DJ are in the navy. If anyone can tell me exactly what they do and how much time do they have to practice while enlisted. I'm pretty interested at joining seeing as I am going to be 21 next week and still don't know what i really wanna do. I'm also curious as to what they don't allow you to have in the navy such as piercings/tattoos.