Q: upgrade from iOS 8.4 to 9.35 or 10.0.2 on iPhone6 ?

I have an iPhone 6 running iOS 8.4.

I have read that it should be upgraded to iOS 9.3.5 before upgrading to iOS 10.0.2

Is this so? Have the risks of bricking been fixed in iOS 10.0.2?

If so, after downloading iOS 9.3.5, how can I install it?

Do I use the iTunes "restore" feature to "install"?

Is that allowed? Is it still being "signed" by Apple?