1. Legally, they do. If they provide an incomplete list, they’re accountable. That’s why it took so long for all the companies to get on board. They had to ensure all their internal processes could not only provide access to the data BUT also delete it easily upon request.
2. So I haven’t done it, but you should be able to tell what they’re doing with the info by way of what the info is. Like if it’s songs and apps you’ve purchased, that’s likely to ensure you can redownload them, stuff like that.
3. And really, if you’re already not in the mind to trust anything Apple provides, how would them “imparting details” help in any way? “I don’t want the information that they give me, I want them to give me the information they’re NOT giving me!”
4. Public information like wiki OR other data provides they’re contracted with? Siri does that. Public information like Google, Google’s not going to allow that without tracking.