Does iOS backup include the OS and related questions I had an iPad stolen recently. I had deliberately not updated the iOS as an app I used was not being updated and worked well on the old iOS. 

Now I need to restore the back up to another iPad. I thought this would be easy but it seems not. 

For the app I want to use to work I need iOS 8 or earlier. Specifically I had 8.4.1 but it was the upgrade to 9 that killed the app. 

I am unsure of a few things and would value some advice:

Does the backup include the iOS? Ie if i buy an old iPad that can run ios8 will the backup automatically include the iOS? Can I just restore and get everything back. 

Or will the backup just add apps and data to the existing iOS? In which case will it refuse to do it if the existing iOS is less than the 8.4.1 with which the back up was saved?

If this is the case I need to put iOS higher than 8.4.1 yet lower than 9 on an iPad and then restore. How can I do that?

Thanks for any help. I have a lot of work in this app so any suggestions are welcome. 

J
No, the backup does not include the operating system. However iOS can be easily downloaded from the internet, so that is not a limiting factor in itself.

The main problem is that you cannot downgrade an iPad to iOS 8 at all. The original iPad only supports up to iOS 5, and the next-oldest iPad - the iPad 2 - supports iOS 9. As it is only possible to downgrade to the iOS versions that Apple actively is signing, which only includes the latest versions available for the hardware, you're out of luck.

Your only possibility is to buy a used iPad that has iOS 8 on it.

I would recommend instead getting an iPad with a newer iOS, as there's serious security implications to running older iOS versions - and then search for a replacement app, or ask the original developers if you can convince them to update the app for newer iOS versions.