Consider this: the first iPad is not supported by any new iOS version. See here http://en.wikipedia.org/wiki/List_of_iOS_devices (scroll down to Highest Version of iOS supported).
There you read that the 1st iPad can only be updated to iOS 5.1.1. If you already got 5.1.1 on it, then you can't go higher.
If the apps stop working, just do not update them. Problem is once they stopped and deleted the older version which already worked, you can not go back, because you usually don't get your hands on old app versions, except you kindly ask the app issuer.
But you can check the MEDIA folder of iTunes where the apps are stored. If you still got any older version of an app, you can delete the new version and add the old one by moving it to the "Automatically add to iTunes" folder.