Was at the Royal Festival Hall a couple of years back where they showed The Great Escape with Peter Bernstein (the composers son) conducting the BBC Concert Orchestra. And yes they played the theme tune as an encore. A fantastic evening.
Double wall all the time. Always. Standard boxes double up on the large flats of a set, but I feel its better to have the strength in the sides and corners.
My bad. The base and lid boxes I get from qickbox.co being for the large UCS sized sets. The ASC ones are for the medium (Osprey sized) boxes. Type 0409 and yes I'm happy to pay around £2 a box to make sure a high value set gets to the buyer undamaged. Top tip... Fold the short side flaps on the outside of the box so that the set had four flush sides against it and then the flaps act as additional corner protection.
I'll second the boxes from ASC. nothing like a custom slip over twin wall box that gives quad wall on the sides. Feedback from buyers has always impressed.
Without being sarcastic, if you have to ask that sort of question then maybe this is not where you should be looking to make money.
That said, identify all the major sellers of Lego in your country and watch the pricing....