Yes, don't go without one. Otherwise there is no guarantee on time or if you'll get in at all.
No
Really depends on the day and time. I went last Saturday around 2 PM and walked right in. But if there's an event at the parks, a holiday/peak vacation times, or around dinner time and weekend nights it can get pretty crowded. Basically if you know enough in advance, I'd recommend booking if possible! Lunch time is probably a bit safer for walking in. Hope this helps!
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