2. How can they delete the data associated with the above?
3. Info on how they group personal data from WhatsApp, FB and Instagram
4. Who do they share such data with?
5. Who within FB is responsible for privacy policies, etc.?
I feel like this is a misguided notion. Facebook doesn't need to create "shadow profiles" for anybody to achieve the same effect: they can just pull together the data on-demand (e.g. say when you create an account, they could scan others' contact lists for a match for your name), without aggregating them together into a 'profile' beforehand. Unless you really intend to ignore that possibility (which I doubt, given the effect would be exactly the same), you probably want to approach it differently than talking about 'shadow profiles'.
You are right that some fly by data might end up in a server log somewhere but those aren’t kept around for long...if they are kept at all at Facebook scales
Storing and computing data is very expensive and risky at FB scale so they will only keep around what they actually need for as long as they need it. Meaning that data gets send to the server, gets aggregated and then deleted.
An exception of course is content generated by users such as a newsfeed post, as is the nature of the product that content stays around until users delete it
Funny how this question always seems to generate distracting and misdirecting responses.
The simple fact that detractors seem unwilling to address is that FB and countless other internet advertisers are stalking billions of unaware people on a micro level using all sorts of shady and opaque techniques and compiling the most detailed psychological profiles on the most number of people in history.
The public has only just begun to contemplate the massive national security and mental health problems that this mass stalking and manipulation creates.
On 5, I would hazard that it's those teams. Of course, the buck stops at zuck.