Jennifer, since no one has responded yet, my take. I've done this many times.
In iPhoto, make an album, get pics into it however you want, arrange pics into sequence. Select All or just Select entire album; File>Export and set size maximum to 720 or a little more. iPhoto can number sequentially for you. After Export, in Finder, drag folder to FCP Browser and you're ready to edit them into Timeline. Drag the folder to a new Timeline and all pics will default to the length you set in FC Prefs.
Good luck!
Phil Cramer
Indianapolis