6) How many formal nights are there?

There's usually one formal night for every 7-night cruise.  We also hold a formal night on shorter cruises, less than seven nights.
The formal night on Marella Discovery, Marella Discovery 2, Marella Explorer and Marella Explorer 2 has been replaced with a Dress to Impress Night. This is still a great chance for you to get dressed up - how dressy you go is completely up to you.