Here is how I see it.
What they are monitor are (In my Opinion and based on sites I have read)
Internet searches using bing doesn't mater on the browser.
Email sent using outlook.com or outlook servers which has also been the case.
What application you use & how many times you use it.
Applications you install.
As for as personal information
Words or phrases type in the Search box only if cortana is enabled.
What you uploaded or keep in One drive which has also been the case.
Apps you purchase including free ones.
Credit/debit card info only for apps that require purchases this is where your name comes in.
Passwords related to Microsoft Account or saved using edge/internet explorer.
Bookmarks you have installed using Edge or Internet Explorer.
Send data to law enforcement when required but meaning anything you use on the web, not what you use. Another words, what you are already public with.
Again this is my Opinion and based on sites I have read. I would be happy to use windows 10 daily but I don't use for the moment do to another reason. Microsoft did supposedly removed or modified the device ID number, so you can't be tracked that way.