4) I have operated a flight 4 flights after last deicing, and the fluid was still "trailing of the wing" during flight.
And a comment on your last remark: The fluid giving you holdover time, is designed to protect the flight from the begining of the treatment until the flight is in the air. There is no protection from the fluid airborne, there are other means for that, and there is no protection on the following flight without a new fluid treatment.