If you purchase the all day pass can you come and go throughout the day or is it over once you leave?

You may come and go as you please.

Yes, you can come and go. They give you a wristband marked with the time the pass you bought ends. If it's all day, it'll say 10 PM or the closing time.

I think a hand stamp or wrist band let's you come and go as we didn't leave so check it out.