Do you have to reserve or pay to camp here?

As of 2022, there is just one walk-up site (#12) as all of the others have been turned in to reservable sites. You can always check a campsite's Availability Grid on recreation.gov if you want to see if there are any unreserved campsites on the day you want to arrive. If it is within 3 days of the current date - those campsites turn from reservable campsites to First-Come, First Serve. That doesn't mean that someone else hasn't come up in person to claim those sites - and generally - you cannot find out of those campsites are occupied unless you GO up there in person.

Not usually. Unless it's a busy time like holidays.

You do have to pay for your site, I believe its 26 a night for single site and 52 for a double, which isn't much considering this site is beautiful has water spouts,bear boxes and vault toilets. I would reserve if you can cuz this ones full every weekend in summer, also need to reserve 2 to 3 days in advance minimum, You can do walk ups Sunday through Wednesday to chance a spot but mind that Thursday through sat are probably booked so might have to leave if you plan on staying into those days. But there are 8 unreserveable sites for walk ups here.

It is a pay camp ground. It's better to have reservations on the weekends but there are 8 walk up sites that you can just show up and if there open rent them. They can't be reserved.