First....don't worry. He'll be fine and have a ball. Our daughter has been in Southern Siberia for nearly 2 yrs and I don't expect her to ever live in the states again.
I only ship what she cannot get there. The list is getting smaller as they are beginning to get more western things. Books, DVDs of TV shows and movies, magazines & music CDs and picture CDs of family and friends make up most of my care packages now. Like Barbm said, fill every air hole with hard candy. Once I was sending lots of craft supplies for the orphanage and poured beads in to fill up the box. I warned her to open it on the bed so she wouldn't lose anything.
And send him a list of everything so he can check it off. She has gotten everything I've sent except a bottle of cologne. It was taken out of the box and they left everything else and retaped it. Hope somebody smells good. Later, I sent another bottle but put on the form...toiletries...I didn't specifically list cologne.
I use the flat rate priority boxes and it takes a month to get to her. Might not take that long to get to Korea.