Correct, no waterfall at Koko Crater

I would not. Muy peligroso.

Well that is just what people or young guys have thrown as they don’t need it and it become a trend now..

It’s not really an official trail so it’s open all the time.

Yes it is safe. If you are apprehensive, just take it slow :)

I wouldn’t recommend it. At one point there is a large gap, and children can fall through. Also, the hike is very very physically demanding.

This might be a late reply but you can do this hike without a guide. It’s located across the street from Hananuma bay (popular tourist snorkelling spot). Tips: Arrive early i.e. don’t attempt at the hottest part of the day. It’s a hard hike up & down like being on a stair machine for two hours. Avoid carrying heavy backpacks. Bring lots of water. You will likely be sore for two to three days after the hike. We took a bus to get there from Waikiki beach.

I don’t think so. As long as the person is fit. You can always go and check it out and do the first few hundred steps and see how you go.

Don’t start later then 4pm, otherwise you will have hard time coming back in the dark.

Yes. I did it on my running shoes and I saw people going with flipflops (which I don't recommend). But I guess converse sneakers are fine. Most important thing is to go really early when it is not warm and bring enough water.