> 7. To disable telemetry (...) Why should I disable that? What does it do? My understanding is that it's only statistics on data usage, which I find useful?
If cortana wants to automatically recommend appointments from emails? Guess what? She has to read your emails.
If you want to be blocked from downloading malware? Guess what? You have to check with a central db first.
etc
Apple, Google devices etc have had this stuff on for ages.