In re: the confession dial, I think the Time Lords tampered with it. It’s his bespoke torture castle, but he didn’t recognize the trap for what it was at first, which he would have done if this was how confession dials normally worked. I suspect he told it the truth earlier, before giving it to Missy, and that’s how the trap version knows when he’s telling the truth. The essential purpose is perverted, though.
Time Lord tech all the way: bigger on the inside, closed loop, time passes inside without passing outside. I wonder when he figured out it was the Time Lords. Would he have recognized the teleport technology? How surprised was he to step out onto Gallifrey?
I think we won’t know the full meaning of “rethink what you know about regeneration” until after next week– that trailer!