Brad,
The decoder can be found
here. You type in all your car's details, and it will identify for you the original colours, where it was made, where it was assembled and when (if you still have the original engine number) etc. It might be able to give you partial information on the FB, but it was designed for FE/FC.
You will also find
here explanations of the ID plate info that might be of some help with your FB.
The Van and Ute had no key-hole on the driver's side because it used to be illegal to get into a vehicle on the traffic side. The Specials had key-holes both sides so you could get in on the driver's side in the comfort of your garage/driveway. A quaint idiosyncracy...
Fold-up seat was always an aftermarket accessory, typically made by the same body-builder companies that made the camping body front seats and so on.
Hope that helps,
RET