Re:restoring exterior of stepvan
Theres a 3M eraser wheel that does great for taking off old lettering glue (I have an old Snap On Truck-same song and dance).
As for refinishing you might have to do a very light sanding in order to get the oxidation off then buff it from there to your desired finish. That way it will all be even and clean.
On a side note how did those propane brackets work for ya?