Sorry - you cannot bring liquour or beer on board. Only wine and champagne. If you want liqour for consumpation in your cabin, you can order it through Ship's Services
HAL no longer has kiddie pools for the younger set. They have closed the ones they had on the other ships due to health regulations. I don't think the Vista ships ever had the splash pools. Babies/children in diapers are not allowed in the other pools. Sorry.
No, they do not have theme costume nights.