O.K., I, too, think
I've got a solution to my problem. I noticed that the Fedora release notes said that the livecd-tools
included a tool to copy the LiveCd boot information from the iso
image to a USB stick so the stick would be bootable. That implied to me that the LiveCD (as magplumber
had mentioned) could handle the USB and Serial drive problems, and that it was differently done by the Fedora install media.
So, since I didn't really need the drive I'd pulled from the laptop, I decided to wipe it and install a fresh Fedora from the LiveCD, setting it to boot from the USB drive. That seems to have worked.