I must say that this topic has more than its fair share of misinformation.
These are the bits that I know to be true.

Whether or not you can roll back drivers, disable Windows features etc depends not on whether you paid for it but on the version.
Which version you get depends on your version of Windows 7 or 8.
For example, Windows 7 Home premium entitles you to Windows 10 Home.
Windows 8 Pro to Windows 10 Pro and so on.

As to privacy, Microsoft have one policy which can be viewed at their site.
It applies to all Windows versions.
If that is unacceptable to anyone, they need to look for a different OS provider altogether.
While I cannot see into the future, unlike some seem to be able to, Microsoft have said that there will be no charge for updates to Windows 10 even though for one year it is offered free of charge.

Windows 10 ships with Direct X 12 and for me it will run any software from Direct X 9 upwards.
This naturally includes FSX and FSX Steam in Direct X 9 and Direct X 10.
I don't have P3D.
I don't have anything left that needs Direct X 8 or lower.

@ Post#6
The larger FSX can easily be resolved by accessing the properties tag for all users of fsx.exe and ticking the "Disable display scaling  on high DPI settings" box.
Windows 10 did this for me.
While you're there, tick the "Run this program as an Administrator" too, then click on Apply.


Finally, I have it, everything that worked before works now, often a little better.