OCI card related questions

[immihelp]

Dear Sir/Madam

We are applying for OCI card (to Embassy of India DC) as a family.
Two questions with regard to use of blue or black ink pen and self-addressed stamped envelope for return mail. Does blue ink means real old-fashioned liquid ink only or can it be blue ink ball-point pen? How many dollars stamp should be affixed on the envelop?

Thanking you with best regards

[immihelp]

1. Ball pen is OK. It does not have to be fountain pain.

2. Just first class mail.