Go to Preferences > File Handling. You can control the resolution of thumbnails and have many pages are saved.
You can view those thumbnails in Adobe Bridge. If you're on a Mac, you can purchase Art View from Code Line to also view your thumbnails in the Finder. (An earlier version of this was sold as SneakPeak Pro). There is also a version for viewing on iOS devices from Code Line.
As far as I know they are only viewable in Adobe Bridge.