Rolls of duct tape vary, tape made for hardware purposes can be much longer, but crafting duct tape by the Duck (3M) brand are sold in lengths of both 10 and 15 yards.
You can not tape yourself into a box, but you can tape the box shut if you are small enough to fit into the box. (Taping yourself into a box is not recommended, it is not safe)
Taenia saginata, the beef tapeworm, can grow up to 40 feet long (12 m); other species may grow to over 100 feet (30 m). (Wikipedia)For the source and more detailed information concerning your...