Yes you can, just hold on to the stub that they give you when you pay. Not just that, but I believe you only need to pay once per day to access all the parking lots - so you can also park at a different theme park without paying again if you need to.
Yep, as Interpol stated you pay parking once a day. As long as you have your receipt you should be fine to park at the same park or another park that day.
Yep, as Interpol stated you pay parking once a day. As long as you have your receipt you should be fine to park at the same park or another park that day.