In my humble opinion you would be crazy to offline this in FCP if you have the option of offlining on Avid.
Still photos will not appear in any EDL. EDL’s only understand 1 video layer and only sources that originate from tapes.
The best way to move projects between FCP and Avid is Automatic Duck…but I dont think it would work that well considering all the stills you will be using. FCP and Avid handle stills completely differently….Avid does not import hi res stills the way FCP can.