I hope I can help with some info.
ME: I have been with win form 3.0 till present. Along with DOS. I am now 59. Many years with Win.
I also have a degree in Networking.
With that said,
IF and ONLY IF you have reserved a copy for download will you get Win 10 in your updates.
If you did reserve a copy you can cancel it.
You should see a "white window" in the lower right corner of your pc.
Click on it, in the window that pops up go to the Left Top and click on the 3 dashes.
Then go down to " view confirmation", the next window, on the left side click on "cancel reservation"
And now you will NOT get Win 10.
If you do want it, and you did reserve a copy you can delay its down load Before July 29.
Check in the window at the lower right of your pc. You can find how to delay the download.
Hope this helps
P.S. you cannot block win updates in the firewall.