We really enjoyed HHI!
We had our DS17 in tow & he liked the activites, also. Perhaps there is a DIS person who can scan in a schedule & email it to you, or simply call
DVC HHI to email you a copy.
We did see frolicking dolphins, in the early morning hours usually, between 5 am to roughly, 7 am. Right up there near 'parking garage with a drop dead view' under the Live Oaks Lodge (where you'll be checking in). We went in late March of this year.
As for activities, there's plenty of kayaking trips--both DVC & local, if you are a competent kayaker you may want to rent one locally, our guys found the DVC trips informative, but geared for novices--, wildlife walks, B'lou Crabbe magic shows, pre-teen & teen pizza & movie outings (divided into age groups--DS17 found this a fizzle, as there weren't enough kids his age present), Hidden Mickeys Walk; DVC owners wine & cheese get together; low country boil (great, but bring your own shrimp cocktail sauce

) etc
Yep, no fireworks, but we loved HHI!
Took us a couple of days to wind down, but we enjoyed it so much we stayed an extra night!
Jean