Tinribs, at the risk of provoking further outpourings from erstwhile contributors, may I point out that your last 3 'questions' assume that the aircraft was under control by the pilots at the time. For alternative possibilties, delve into the history of the Chinook (and look up the history of Undemanded Flight Control Movements within US Army and RAF service) if you like, but the sad fact is that the questions are simply not capable of being answered because no evidence survived. Two Air Marshals thought otherwise and came to a convenient (to them) conclusion; they have since been shown to have been wrong.
As an ex SH pilot with time in NI on Wessex and Chinook, I am not sure I follow your point about operational missions and other trips. I treated all lives with equal respect, no matter what the nature of the flight; I wasn't aware of any crews who acted differently.