Interesting to read the above.
My (UK long-haul) company policy is to maintain present squawk "if in contact with ATC", unless ATC asks us to change it.
Regarding heading change - no company policy that I know of, but the general feeling is to maintain present heading if in radar coverage. If we do have to change heading for some operational reason, then make it clear to ATC what we're doing. Outside radar coverage, turn away from the airway centerline.
Hope this helps,
t