You can get a PDF copy of the Form W-7 from
Internal Revenue Service. The mailing address for the W-7 is contained in that form.
You have NO tax liability to the U.S. if you are not conducting business in the U.S., so no tax return will be required.
Now, to get the ITIN, you will need a letter from the company to whom you are affiliated in order to apply for the ITIN.
However, contact the company and ask if they will accept Form W-8BEN instead. The Form W-8BEN can cite the requisite article in the U.S.-India Tax Treaty regarding business profits and claim an exemption from any withholding on any money paid to you. The W-8BEN is good for three years and would negate the need for you to get an ITIN.
If you submit the W-7, the BEST form of identification is a notarized photocopy of your passport plus an apostille from the Indian government agency that issued the passport. If the passport photocopy is NOT an option, you need to submit TWO types of identification to the IRS. The acceptable types of identification is listed in instructions attached to the Form W-7.