FYI I think I figured it out successfully. Again, thank you for your concern. I will explain how in case it might be useful to someone having the same problem.
For starters, I was most carefully following Focus Enhancement's instructions, "Panasonic HVX200 to Firestore FS-100 tapeless recording workflow", a separate document from the FS-100 Manual that F E Support emailed me. The problem was that the clips were not showing up in FCP's Import Panasonic P2 window.
A white paper Apple publishes, "Workflow for Final Cut Pro and the Panasonic AG-HVX200 HD Camera" and the part, "Importing P2 Footage into Final Cut Pro" explains different ways one can import footage from a P2 card. #5 discusses the condition in which the files have been transferred from a P2 card to a hard drive and how "... the clips are organzied into separate folders contained within a Contents folder". This proved to be key.
Following FE's work flow, one would have done the "Organize P2" step, which organizes the clips into separate folders in a Contents folder. Opening up the FS-100 HD in the Finder, this was indeed apparent.
Continuing with Apple's white paper, it was a matter of a) entering the name of FS-100 HD in the Search Field of FCP's Import Panasonic P2 window and b) MANUALLY navigating to the FS-100 HD and selecting it. The clips then appeared in the Import P2 window. This is not adequately explained in either the FS-100 Manual or FE's Work Flow.
A word of warning: the illustrations of the Import Panasoonnic P2 window in Apple's White paper do not correspond to the window in FCP 5.1.2. so one has to extrapolate.
macbook Pro 15" Mac OS X (10.4.8) FCP 5.1.2, FS-100 Portable DTE Recorder, AG-HVX200 Camcorder
macbook Pro 15" Mac OS X (10.4.6)