I don't really think that there were a lot of props in the streets of America part. I would think that everything was stick built to create the facade, even the signs on the almost buildings. The backlot, absolutely thousands of things, but the streets themselves I'm thinking not so much. There was a lot of equipment that needed to be salvaged from Lights, Motors, etc but mostly big ticket items like the vehicles which, if I had to guess, are currently on their way to Paris to replace older equipment that is currently there. I'm also guessing that archives gets all the time it needs and may be one of the biggest culprits in how long it takes for demolition to be completed. We as impatient fans tend to over-simplify the process, both in salvage and safety to taking down huge, very strongly engineered buildings.