Here is a more in-depth analysis of windows 10 and what is sent to MS
http://aeronet.cz/news/analyza-windows-10-ve-svem-principu-j...
For those who don't speak Czech:
-It sends all text you type anywhere (not just into search) every 30 minutes to MS. If you type about a holiday to your blog, next day you'll see holiday ads.
-Every 30 minutes it sends your geo-location and network information.
-If you type a telephone number into Edge it sends it to MS after 5 minutes.
-If you type anywhere in Windows a name of some movie, Windows will start indexing all your media files after a while and will send it to MS after 30 minutes of your inactivity.
-After installing W10, it will send about 35MB of data once.
-After turning on your webcam for the first time it sends data to microsoft once.
-Everything you say is transferred to MS, it works even if you disable and remove and uninstall cortana. Parts of Cortana are needed for the core of the OS to run.
-Voice is transferred every 15 min, 80MB of data.
-After 15 minutes of your inactivity or when screensaver is on, network activity ramps up and everything else is being sent to MS.
-Blocking in hosts doesn't work, IPs are hardcoded into their code and DLLs.