coop culture Colosseum underground tickets

All tickets purchased in advance are "skip the line tickets", in fact the only line you can "skip" is the line to purchase the tickets! Then there is the security line and nobody skips it. Then you are in. If you are trying to skip the security line you'll have to become an head of State and visit Rome during the next G20 summit. Or Pope.

Yes, all kids younger than 18 from all over the world enter for free, as long as they have a passport and a CDC card. It's written on the coopculture site, but thanks to Covid containment measures they'll have to pay the € 2 reservation fee.

If you are from the US and under the age of 18, you are free????

Not for every type of ticket/tour. You have to reference the details of each option available.

I have also read that you need an additional ticket for the colosseum.
Would this be just a standard ticket?

Not sure what this means. Most tourists are mostly interested in the Colosseum so purchase the general entry or tour options which include it. A "standard" (general-entry) ticket does NOT allow you access to the underground or arena.

Can we really get into the colosseum, plus see the underground level,
at a specific time, for 24Euro/adult and free if under 18 years of
age?

Yes, if you buy the correct ticket.
https://www.coopculture.it/en/products/full-experience-ticket-with-access-to-the-arena-and-underground-of-the-colosseum/

Thank you for all the good information. I think I am beginning to understand how this works. My only other question is, does anyone know when the tickets actually go on sale?

Rene, I believe your trip is next summer and who knows what sort of ticket-release schedule they'll have by then. All I can tell you right now is what I'm seeing on the coopculture site. The 24-euro tour you're interested in is being sold a month in advance; the furthest date out that tickets are available is Dec 12th. That could change so keep a sharp eye on the website. Tickets will also disappear faster once available for high-season (spring/summer/fall) tours.

This is important, though: it states in the info for the tour that you can only book 6 tickets for the same tour at the same tour time. If you're looking to book for all 12 of you, someone else will need to book the other 6, and you may not be able to get all of you onto the same tour at the same time.

Something to consider? With 12 people, it would likely be easier and very possibly more economical to book a private tour with a dedicated guide for your group. Francesca Caruso is highly recommended but also much in demand so may already be booked but you could try her? Sonia Tavoletta has also been recommended, and there are others listed here:
https://www.ricksteves.com/tours/guides

There are probably still others that RS posters have used. Just be sure to make it clear to the prospective guide that the tour must include the underground if that's a gotta-do for your gang.

Thank you so much Kathy for the great information. I am going to look into everything you mentioned. Truly appreciate it!

You're welcome, Rene! I wish I could offer from-the-ground help but COVID has kept us home for the past couple of years. ARG! The best I can do is to share info from posters who have been there recently, and from what's stated on websites of the official attractions themselves.