I am working on a project and need to build a custom page similar to "Page" in elgg.

I am sure there are already solutions provided in this community pages.

But I searched and couldn't find the helpful pages.

Honestly I do not even know what to search for.

Please just point me to the right documents and that will be very helpful. 

The different between already existing "page" and my custom page is

1. I need to add "Date of Incident" a date field.
2. I do not need the tags field
3. Should be able to upload photos into an album like, and be attached to this page
   1. When you view this page later, the photos will be right there with the content
4. The view access should be provide by individually "selecting the existing members" (not just friends) and also "by giving email addresses, separated by commas"
   1. May be like 2 separate fields – add by name, add by email
   2. The members will be able to see the page when they login
   3. The non-members with just the email provided will get a special link and they can view by clicking that link only
5. The logged members viewing this page should see a button similar to "create a sub-page"
6. The sub-page should have all the fields like the main page, except for the access fields. The access properties of the main page apply to the sub-page also.

Thanks in advance for any help I get.