I would say that since Japanese people usually eat rice at least once a day, and often three times a day, make sure he has a chance to eat white rice and Japanese food at least once in a while.

Find a nice Japanese restaurant in Dallas so he can introduce you and your family to Japanese food.

Here's one of the best:
NOBU

umm.... thats like way to expensive dude...

Don't complain. It's a once in a lifetime chance, isn't it? Save up some money and you can all go there together as a family on the last day or something.

Also, given your initial description I wanna go ahead and say: don't try anything... untoward. I know how some Americans are about Japanese boys. :rolleyes:

I like Burkhartdesu's post about his favorite memories. Give your host brother something like that. Especially show him the things your area is famous for. Don't be afraid to go do touristy stuff, because that's kind of why he's there.