A: Correct. You previously had to buy the device that would work on your specific provider but now they all use the same technology so you just activate on the provider of your choice.
A: Yes, I have Verizon service on mine. You just stop by a Verizon store and they pop in a SIM card for their service.
A: With an internet connection and an Apple ID, you can make and receive calls in the FaceTime app (first sign in with your Apple ID, or create an Apple ID, if you don’t have one).
A: 14.4.2
Q: Can I swap the sim from my current iPad?
A: undefined