IPad – suppress update notices for apps that require a greater iOS version than the iPad supports

You will need to use the original Apple ID with which the apps were purchased. Only then restore from the backup made (preferably the backup made via iTunes). This is the only way to retrieve the app data associated with the given application.

my daughter showed me an easy way to install the older Apple store apps. you simply log onto the apple store using a computer (without the iPad connected). find & download the software to the library on that computer. once it is added to your library, goto the app store on the iPad & install the software... since the newest version won't work for the iPad, it will ask you if you would like to install the latest compatible version. this seems to work for 85% of the apps out there (as long as there was a prior compatible version). :)