N.A. DS Lite in Japanese instead of English?

Hello,

This may sound like a crazy question, but can you switch a North
American DS Lite to Japanese language? The reason I ask is that my
wife really wants one. Now, we live in Japan, but you can't find them
anywhere here, they sell out in minutes. So I was thinking of
importing one from Canada or the US for her. But I think she would
like it in Japanese, not English. I have heard that you can change the
language to English on a Japanese model, can you do the opposite for a
Japanese model?

Also, the games are all region free right? Oh, one more question.
Does anyone know how much the DS lite boxed unit weights (for
shipping)?

Thanks!

James