Osaka Kaiyu Pass and Kaiyukan Aquarium

Hello! I have a few questions about using the Kaiyu Pass:

1) How far in advance should I be trying to get the Kaiyu Pass from a local station (e.g. Osaka Station)? Is the day before the planned aquarium visit early enough?

2) With the Kaiyu Pass, can I enter on any arbitrary day? For example, if I plan to enter next Tuesday but end up only going next Thursday, is that a problem? (I am aware that I can't mix metro use and aquarium entry on different days)

3) With the Kaiyu Pass, can I enter the aquarium as soon as it opens?

4) Can I leave the aquarium – say, for lunch – and then re-enter afterwards, on the same day, using the Kaiyu Pass?

Thanks!