Maybe it is just my luck, but the airport USBs never work. Even though they are now placed in very convenient spots around the seats at the gates, they are usually broken or don’t seem to be getting electricity. The best bet to avoid this problem in a hotel room, train station or airport is to carry the socket part so you can use good ole outlets rather than hoping you’ll find a working USB port.
Plane headphones are typically really bad quality. You will likely want to bring your own on. This is especially important if you have the new iPhone with the different headphone connection than what airplane entertainment devices use.