Your half faces you, theirs faces them.
No. Translation needs a connection. Transcription happens on the phone, but the translation itself does not.
No. Speech is transcribed on the device and the recording is never uploaded or stored. Only the transcribed text is sent, in order to be translated.
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In the iOS Settings app, under your name, then Subscriptions. Cancel at least a day before the next renewal. Cancelling leaves the app working until the period you paid for runs out.
So the person across from you reads it the right way up and answers on their own side, without anyone passing the phone back and forth.