As for the tatooes, just make sure your son keeps in mind they are "forever" and it's wise to get them where they can be covered. My husband has tats up both sides of his arms and on his back. He has to wear long sleeves even in the summer to cover them up for work.
He should also remember that alot of places will make you take out your piercing for work (if it can be seen). It won't heal if he has to keep taking it out. If he's going to get one, it should have plenty of time to heal before taking it out. I've had my nose done twice, my belly button done three times, my eyebrow once, and my tongue once, and the tops of my ears on both sides. I think out of all those, the nose was the easiest to heal. The tongue can get infected easily if you don't keep it extremely clean.
Most guys get the nipples pierced, the lip, or below the lip, or the eyebrow. I've never seen one with a belly piercing. My nephew did the nipples and the eyebrow with no problems. :0) Cleanliness is the main thing with piercings. With the tats, you want to keep them covered in Neosporin (sp) and keep them covered from the sun.