Welcome Dan
1. Different WFC systems use different cores and VIC designs, there are different ways to accomplish the effect, however elusive... The toroid was mentioned in one system, the bobbin type was the latest, most advanced VIC design, possibly worthy of superseding all previous VIC designs. Toroid VIC's are not economically simple (mass production), while bobbin VIC's are. The context of Stan's development spanned from 1975 to 1998, and over the years his systems advanced, so keep that in mind when trying to sort out what is what and what goes with what, some details are separated by years of advancement.
2. The taper resonant cavity is part of an advanced and complicated system, and there are not many people there yet, see Hardkrome's project section.