Especially Number 3 - totally against the Fourth Amendment. I get pissed off when the Wal-Mart greeter asks to see my receipt as I'm leaving with no probable cause, I flat refuse. I'd rather see them call LEOs. I'll waste all of our time if that's how they want to play.
Sorry, got off topic for a second there...
Yeah, on one hand event organizers in your example could say "Don't want your shit searched, you don't have to be here. Leave"
On the other hand, if it's a public park then they don't have the right to search without probable cause IMHO, not even "for reasons of public safety".
