Okay. Your wife should present the following documents:
1. Marriage certificate
2. Original birth certificates of all them
3. Photos of you with your family
4. Proof of financial like western union or other transfer bills
5. Filed forms of i-765 and G-325 that the us consulate sent to them.
6. Must do the medical exam with a qualified doctor required by the us embassy
The questions might be:
When did you get married, the date of the event and the place.
What is the your spouse date of birth
What is his USA address and his job and position.
Etc... just about your family