When you are in your sailing click on the ship to left and then at the bottom of the screen you will see it . Or you just log into you booking on the website
I would contact celebrity otherwise all you are getting is people’s personal opinion and not up to date policy. You have to do a health form the day before you sail
I would say the Sky Lounge is where some of the entertainment events take place rather than a night club . On my recent Infinity Cruise it was empty by around 10.30/11.00. No real night clubs