For the privacy, there is a way you can get them not to join other servers. I
play minecraft, so I understand the whole obsession. May I recommend setting
some rules with your child? Maybe only twenty minutes a day to play, because
that also gives adequate time for them to do things on the game. It is very
educational, and is at the top of my video game list, but time...it's hard.
My best advice is to get him hooked on books.