Mark,
Whew... thank you for patience. I did a bit of investigation tonight and was able to get things going. Fortunately, there weren't any code changes necessary, just some shuffling and configuration settings to do it. Here's what I did:
* I moved the JFBCSystem plugin *after* the wbAMP plugin. This got rid of the 404 error because the /amp at the end of the URL was causing some problems for our parsing of the URL.
* After this, the page loaded, but a bunch of JFBConnect Easy-Tags showed on the page, like {JFBCFacebookLike ...}. It was ugly. In the wbAMP plugin, there's an option to disable specific content plugins from loading in the 'Cleanup' section. I used that area to disable the JFBConnect - Content plugin on AMP pages
With that, voila! All seems good! Please test and let me know how it goes, but the changes seemed pretty benign, so hopefully it's smooth sailing from here.
Thanks,
Alex