Agreed. A few of my physician/nursing friends mentioned that they see these kinds of injuries on rare occasions and have always been attributed to patients in serious mental/emotional distress, so this level of desperation is unfortunately still out there.

It could be a desperate suicide attempt. The magnets get trapped in the bowels by sticking together at various points, necrotizing or rupturing the intestines or other tissues, which can cause peritonitis or ultimately sepsis, which can be fatal.

Any number of places. It could have been a stowaway in luggage, imported livestock, etc.