Can anybody be able to come there anytime because it's a famous ghost adventure person so that's what I wanna know?

As long as they are open you can go. The caviat is that no one under 16 years old. People 16-17 need to have an adult with them.

You have to be 18yrs or older in order to go inside museum. There is a gift shop on back side that I think anyone can go into

Yes anytime. Sometime Zak is there. But from 1pm to 9pm you can go. I've been twice and it was a different experience each time. Really enjoyed the history of it.