Only some of the campsites, the rest are walk in. https://www.recreation.gov/
Yes, and you can call to reserve over the phone if you have a card, or online. Or you can do a walk-in, but there is no promises of a campsite.
Yes, go to recreation.gov and search for McWilliams campground
Reservasions yes
Most of the campsites can be reserved through the system on recreation.gov. I recommend planning months ahead of time to get the best sites.
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