I was just wondering if FaceTime calls show up on my carrier's (Sprint) bill as a regular call, like the number that was FaceTimed and when and the length of the conversation.
Facetime uses Wifi or Cellular data so will not show as regular calls on your carrier bill.
You can use FaceTime on any of these devices on Wi-Fi: iPhone 4 or later, iPad Pro (all models), iPad 2 or later, iPad mini (all models), and iPod touch 4th generation or later (only iPod touch 5th generation or later support FaceTime audio calling).
With a cellular data plan, you can also use FaceTime without Wi-Fi on any of these devices: iPhone 4s or later, iPad Pro (all models), and iPad (3rd generation or later).
Details of your FaceTime call history are stored locally on your device.