IPhone – Is the length of Facetime calls made with Apple Watch recorded

You can add another email address for FaceTime in your iPad:

This will allow you to call your iPad uniquely with this id.

Similarly, you can add another email address to your MacBook Pro's Facetime:

…to my iPad and iPhone simultaneously […] at the same time on each device

You will receive simultaneous calls on all devices with the same Apple ID. This is how FaceTime works and is not due to any action on the part of the caller.

but each time my face was visible

The background to a FaceTime call that has not been answered will be the camera feed from the front camera on the device. This is not transmitted anywhere as the call has not been answered. Any correlation between who is shown on this preliminary screen and the caller is pure coincidence.