Connecting iPhoto to external drive Would it be possible to create iPhoto "repository" on an external USB hard drive, so that every time I would plug the drive I launch iPhoto, I could manage my photos?
If you mean an iPhoto library for storing masters/etc, you can create a second library by holding ⌥ when launching iPhoto. You can create a new library and will be prompted for a location to store it.

If the library is unavailable when launching iPhoto, the original library will be used again (or one created if the original library can't be found).