There's nothing theoretical about it since you never took into account any variables

You should send it back to Sony fast before the lens dries up. That's not normal. I've dipped my Z1 in swimming pool, splashed water at it for a whole day at wet parks, capture underwater photos, dropped it at the pool bed, washed it from my son's puke, cool it down with running water for up to 5 minutes when it heats up and not once has it shown any signs of moisture seeping in. If liquid can get into your phone, you're in trouble though not necessarily now since you say everything works as it should. But that's definitely not normal and you should send it back to Sony.

Depends on how you feel about new/latest music. You can download them but it won't play on any other player but its native one. That's a major dealbreaker for me

Good underwater fun with Z1