Poon,
under 14, no need to go..
they ask you all the family question and what you will do in US, who is your mother in law, her birthday, address, job, how many brothers or sister your husband has.. something like that.. all silly but "easy to trick" question as they have all the answers on their hand.
just relax..
Sure immigration officers know everything and will ask everything.
And you should well prepare for those questions which you asked over here.Explain the reason why he has been denied for entry, why he lost his green card, what did he do that time. Any law paper?? any document??
They usually won't ask kids too much question. They rather concern if your children is ready to go (physically and psychologically).