I am not sure whether this is true for all cameras, but on Windows, many cameras don't mount as standard USB removable storage. Instead, they mount as some sort of special camera component. Unfortunately, when this happens, some downloader software (Downloader Pro, Bridge, etc...) may not be able to read from the camera and apply your naming conventions. I know my G9 has this incompatibility.
As for battery failure and data loss....battery failure shouldn't result in data loss, just inconvenience. During download, the camera is only reading from the card, so they shouldn't corrupt data, even if power fails in the middle of the data.