for knowledgeable persons or consulate officers?

He can file an I-130 for his wife. He may be able to file in China if he is a resident there. He would have to speak to his nearest consulate for information. For the son, he would have to prove that the stepfather/stepson relationship started before the boy was 18 years old. If that is the case, he can also file a I-130 for the boy as long as he does so before the boys 21st birthday. If he waits until after the boy is 21, the boy will have to wait until his visa date is current (there is a waiting period for single children over 21 years old of about 5 years, 7 years for married any age).

If the stepparent relationship started after the boy was 18, the wife will have to file for the boy once she gets her green card and only as long as the boy is single (waiting period of 3 years if he's under 21, more if he's over 21 when filed) If he gets married, she will have to wait to file for him until she becomes a citizen and then the wait is about 7 years.

See travel.state.gov for complete information and contact information for the consulates and Embassies in china.

I am going to have to disagree with part of Smorific's answer. The man cannot petition for his stepson no matter what the stepson's age. The boy's mother can petition for him only after she becomes a U.S. citizen. Most everything else Smorific said is accurate.