Pina colada and fruity drinks will be free. You have up to $15 which the plan covers. Restrictions do apply to top shelf liquor, etc.
If you don't use the shore excursion credit at each port, you lose it per cabin. Just an incentive for you to book with NCL. Some people think they automatically get this money. If you book an excursion, then the credit will show up on your room account.