I applied via mail in NYC a couple of months ago.
1. Only the new passport is required
2. I remember sending only the bio pages from new passport (first page and last page) + latest US Visa page.
3. My passport was renewed in NYC, so I took a money order for $27. My wife's passport was from India, so I took a money order for $42.
4. Self-attested
The processing was quick and I received the PCC within a week.
I just mentioned "Immigration" as the reason for PCC. So, I got a call from embassy asking which country am I applying for and confirmed that I will receive the PCC in two days.
Thanks @american_dream. so we can take just 1 MO for applicant then.
Also where did you mention the reason for the request?