1) Windows 10 is no longer free.
2) Upgrading from W7 to W10 is basically the same as installing W10 from scratch.
3) I don't mind periodic updates as long as they don't screw something up. I also don't care about most of the data that gets reported such as how many pictures I opened.
*Most of this data is put into a database with a number assigned to "you" so it's not like they are looking at porn pictures you downloaded and having a good laugh.
4) You can also DELAY when MS Updates are applied.
Start-> System-> Update & Security-> Advanced Options-> change how updates
*UPDATE:
I can't find the information to change the date on updates... huh. It's supposed to be there (see STEP 1 with link):
http://www.windowscentral.com/how-delay-windows-10-anniversary-update
maybe there is no updates needed so there is no option to change shown?
*The ANNIVERSARY update just happened for W10 which was quite large. It caused a few people problems so I told some people to defer the upgrade by two months.
Summary:
In general, I would leave W10 alone. Other than rebooting your computer rarely to install updates it's not a big deal IMO.
Windows 7 will slowly lose support as time goes on from Microsoft (not just exploit patching) as well as hardware and software. One example is DX12 gaming will only work with Windows 10.