(who else?) Jon Hicksremoves all the icons in Camino’s Bookmarks bar without killing them off in the actual Bookmarks menu. Exactly what I wanted. Thanks to Smokey for pointing it out, and Hicksyfor writing it!
A Firefox extension that fixes its last-tab behavior in OS X when “always show tab bar” is turned on. This was contributed by Simon in a comment on Bugzilla bug 348031, and once I installed it, I found Firefox much easier to tolerate. I hope that this gets permanently fixed in a future version of Firefox, but until that happens, we’ve got the extension to paper over the problem.
My heartfelt thanks to both gentlemen for their pointers and efforts!