The Websites listed below for the USCIS are good for the K1 Visa Petition, and the Ajustment of Status (Green Card) Petition as well.
Set up your USCIS Account here.
Check how much your fee is with the USCIS Fee Calculator here.
Check Status of your petition with USCIS here.
Addresses to Mail your Petition here
Did you Move? Change your address with USCIS here.
USCIS Contact Center – Call Toll Free at 1-800-375-5283.
Time to Schedule your INTERVIEW! Go here to start the DS-160
Travel Advisories – Check what Advisories for your Travel here.