ad 3) I truely don't know what would happen if you lowered the gear at FL 350 doing M .80 - the doors will be gone, for sure! Then the transsonic aerodynamics - I'd say it will be interessting!
Why? gear extension speed is 270/.82 and no altitude limit, once exted its 320/.82
All is type depended i guess, you could use GBAS instead of ILS for example, harder to confuse the flight computers that way
