About caldav, the saddest thing is:
They do support it in windows 10 - for google and icloud. But they do NOT let you configure an account including the username setting. That's all that is missing for full custom caldav support!
Well, that and the 'certificate wall' they have built, were you can't accept a selfsigned certificate and have the calender work with your server. I'll be interested to see how it'll work with letsencrypt ones.
On top of that: Me STILL not being able to sign up for internet calendars (like the one published by my employers controlling software) using username and password... is just sad.