

You can try using the API for getting info on documents: https://www.geni.com/platform/developer/help/api?path=document&version=1
For exporting the GEDCOM export does add some source information so that is probably easier.
For info that is missing from the GEDCOM (info not exported) that you added yourself you might want to look at https://www.geni.com/account_settings/download_activity. But it will take a lot of effort to combine the info.
A GEDCOM is limited in the number of profiles you can export, but you can do multiple exports (from different profiles). There are the ancestor an descendant reports that may be useful to find profiles for an GEDCOM export. But please remember that you can only export a GEDCOM from a profile you created yourself. You can export from multiple profiles but you would need a program to join those GEDCOM files (there will probably be duplicates)
You can probably get the information you want, but it will take a lot of effort.
Am I correct when I think that will NOT get the information about related documents when I receive a Profile structure
https://www.geni.com/platform/developer/help/api?path=profile&version=1
So I will need to call the Documents interface explicitly
https://www.geni.com/platform/developer/help/api?path=profile%2Fdocuments&version=1
And this should include the record-matches and smart-matches connected to each profile?
Since I can actually get info about all other profile information (including photos) from the Profile structure, I was thinking that I should be able to get a list of document-xrefs as well from the Profile interface?
If I need to call the documents interface explicitly I will do so. I just want to make sure first.
I think you can only get documents that way, those sources aren't documents
You might try is you can get any useful info using the revisions (see https://www.geni.com/platform/developer/help/api?path=revision&version=1)
But it would be nice if sources where added to the API.