I've got the first part down, so I'll explain a little for those new to this.
When you create your forum, you'll notice you have the option to use or not use COPPA. This is for two reasons. First, it's a USA law, so wouldn't probably be used outside of the USA. Second, it is only for children under the age of 13. In the USA, the age of 13 is a legal age to use most basic profile websites. However, there are websites that let children younger than 13 join, and if any of those websites allow any kind of information like age or location to be entered anywhere, such as on a profile, then COPPA is required.
If you choose COPPA on your forum, registration stays the same, except it will start with asking if they were born before or after a specified date. This will identify if they are under or over the age of 13. If under the age of 13, then they still fill out and complete the registration process, but when they are done, it will send them an email asking for their parents permission.
The address or fax number for COPPA, is actually supposed to be your address or fax number, but COPPA does not require how the information is sent. If it has to be a signature, photo copies sent as a digital file, actually work best. So I would guess the prepared email sent from the forum, should be rewritten for that.
The (Registered COPPA users) group is great, but roles are missing!!! So I created a forum role (COPPA Users) and a user role (COPPA Users).
The idea is to restrict what they can access and do, to keep them safe and out of trouble.
The parents don't just agree to them using the forum though. COPPA requires you to inform the parents of what information their kids will be able to enter into forms on their profiles and other stuff like that. Then they are supposed to agree to that. So phpbb should have a place to enter that into the email that they get.
And the big question I have now, is can I set up a rank for (COPPA Users) and have that somehow automatically change to a (Registered Users) rank when they turn 13 years old, so they will instantly gain regular member status when they become of age? If not, then phpbb has lots of work to do to actually use COPPA. I never messed with it before, and might not use it now if I can't set it up properly as it should be.
COPPA is only if you will or might have users under the age of 13.
If your forum is for 13 and up, then you don't need COPPA.