Both JR and Keisei's last trains out of Narita Airport are around 23:00. You should be able to make them easily.
Taxi fare from the airport to the town is about 3500 jpy according to
http://en.wikivoyage.org/wiki/Narita . Maybe close to 4000 jpy when you include the late night surcharge.
No idea about late night taxi availability or credit card.