You need to send $335 money order/ cashier check to St. Louis for each GC applicant. (1 for you, 1 for your wife and one for your son if he needs a gc). After encashing $335, NVC will generate and mail Packet3 to your attorneys (about 2 weeks after encashing). You return the PAcket 3 to NVC (1 week mailing). NVC will review the P3 (about 3 weeks..although NVC claims 6-8 weeks). Then NVC will mail th packet to consulate in New Delhi (2 weeks mailing plus consulate entering in the system). In another 4-5 weeks you will get packet 4 with appointment date. Actual CP interview will be in another 5 weeks. So you can expect cp interview about 4 months from the time of encashing. I would guess around December03/ Jan 04....with a slim chance of Nov 03.
Onbiosuly this is assuming everything is smooth sailing.
Yes, you will need I-134 for your wife and son. One each per person.
If you have paid for yourself, wife and son in usa then you just need to carry receipts for your cp interview as a proof that you have made all necessary payment (i.e $335 x 3).
Fees paid in usa cannot be cash. Money order or cashier checks only!
Hope I have answered all your questions!