The ford flash was in the form of a letter that was sent to all of the owners. It is free. Stop by and see your service advisor with your vin. If you need it then it will show up.
Truck needs to be put to stock for this. I would advise leaving it in stock form for awhile after the flash so you can see if there are any issues.
As far as what tune to use for towing..I prefer in stock power as I tow pretty heavy.
08F250 CC 6.4 PSD
Banks 6 gun/ram air
40' Stoneridge 5th wheel, coming in at 15.4K.