I am sorry, slightly different view on:
- screwing the pad down - disputable (!)
- chrome nut on the switch should be on top of upholstery material, I think, as we have seen in BBB and I saw on some other pictures (maybe early-late difference); why would it be chrome if it was covered???
Again: maybe there were different ways for different years/models. Gernold may need to do more digging....
The box floor pad fixing - one of the unresolved mysteries, but I think a lot of mistakes were made when re-newing the upholsteries in this particular place.
Rivet heads, the way I did them: put the rivets through the floor holes down, cover with upholstery material, fold the material, set the hinge, press the rivets form hinge side.