Hermano Lobo,
Don't know anything about q's 2 and 3, but a military accident is investigated by the military themselves through a Board of Inquiry. Occasionally they invite assistance from the AAIB at Farnborough, but not as a norm. Therefore, the wreckage is taken to the nearest suitable site or wherever the BofI is taking place; in this case, Binbrook. Nothing unusual about it at all.