iOS 9 Automatic Downloading If iOS 9 automatically downloads (I know it doesn't automatically install, but it does automatically download) on an iPhone with iOS 8, and I delete the update file from the Settings app, will iOS 9 redownload automatically?
Yes it will download automatically if you don't disable it manually.

To turn off automatic download you need to go to your settings then to the App Store and iTunes Store settings and turn it off :