1. On Sky it is only the Enclave, The smaller ships like Caribbean Princess have a sauna as you describe.
2. You do pick a specific lounge chair.If the sun moves they do their best to move you but can’t always do that.
3 and 4 I don’t know
5. It is open to all adults.
6. Good question, Sky is a busy ship but the area just outside the Fitness Center and the outside walkway near Alfredos or Rudys is good.
7. Normally yes but limited hours. I think Port days there is no lunch I might be wrong.
8. I would certainly ask and my bet is the answer is yes. If they say no, I’d ask them on their Twitter/X or facebook page and see if you get a different answer.
Hope that helps. Have a great cruise. Sky was my first Princess cruise, it’s a beautiful ship.