Samir Mohamed

I just told you, that YOU, the US Citizen, are the petitioner.  Your foreign spouse is the one applying for a visa.  There are links to see which civil documents are required.  Read and follow directions.  

Hi Samir, congrats on your approval! Did you get approved for your I-130 in less then two weeks? If so, that's amazing! Did you expedite by any chance?

You can write, but the child that was born before you were a US Citizen, needed their own I-130 petition.  If you did not file it, file it now.  You can delay National Visa Center processing of your wife's case until the child's catches up.  
 
In the meantime to Consular Report of Birth Abroad for your two children entitled to US Citizenship directly through you.
 
The difference between what happens with your wife and the first child, is that your wife gets a green card upon entry, and the child gets US Citizenship.  After entry, you apply for the child's passport.  That child gets an IR2 visa, where wife gets IR1.  
 
Sorry to hear you didn't do your homework before filing.  You are probably looking at a 1 year delay.

No
 
If the child is a USC not relevant and if not there are no derivatives
 

Probably not

The magic phrase is CRBA, you need to notify the local consulate of your child's birth, get a Passport.
 
Most likely the send child is also a US Citizen.