So if the ticket to the aquarium says 9am, can you show up anytime between 9am and 5pm?

Yes

Yes but they have a dolphin tour that leaves around 10 a.m. check he website to confirm dates and times

Yes.. You are welcome anytime.. Plan to spend 2-3hrs inside to see all exhibits. You'll have 2 blocks to visit and the second one is smaller though.

Any time but there is a lot to see so I'd probably get there early

Absolutely