The procedure to get an affidavit from chicago indian embassy

[velu_morgan]

Hi,
My minor son is living with my parents in india and parents we both are living in US. I would like to apply for a passport for my son in india, for that they need an affidavit letter from chicago embassy(falls under our region) to get is passport india. Can anyone share the experience of getting it like


Do I need to go in person to get the affidavit or
can I apply through mail?
What are the documents required?
Do we have form to fill?
Any processing fee?
.

Please help me & Thank You!