1) Do firmware updates through WiFi only. It's easy to brick with the downloads from iriver (or downloads from anywhere else for that matter).
2) Put books on SD card only. There's at least one known, unfixed bug which makes it go into infinite loop and the device would end up being bricked if it was in internal memory. With SD card you can recover by taking out the SD card.
3) Mods are all available here in this forum. Search for threads with Story HD Mod in the title.
Have fun with the device.