You can reserve and it is first come first serve as well
It's always best to reserve if possible.
Depends on time and season
It's both. Should not be a problem as long as it's not a holiday.
I'm not sure if they allow first come first served, but, i would imagine reservations are highly recommended. We only spent the day hiking, but it didn't appear that on that particular day, there were too many campers.
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