when you visit here do you have to check in somewhere and when do they close?

Dawn to dusk operation. No check-in required.

I just parked in the grass and walked up. I think they are still changing and building more stuff, so that may change.

There is no check in. I would consult the website for hours of operation.

Is a Nice little park. We parked and walked with our Dogs on a leash. Free, no check in.

No check in, check hours on website or what's posted on site. They do have an excellent video presentation on the history of the site that is recommended and helps place a perspective on the history of the site.

No check in