If you update to iOS7 you will lose the previous iPad Pages and it will be updated to the latest version Pages 2.0?
The added complication is that Apple is passing all your documents through iCloud whioch is altering them to the latest Pages 5 format.
Apple is pushing you relentlessly to stuffing up your files one way or the other.
The only way out is to use the iPad as is in iOS 6, or in isolation. Passing documents to your Mac via iTunes or eMail.