I would try turning everything by hand (except crank since.....well it's impossible) and also try giving the water pump pully a shake to see if the bearing let go. Just had that happen in a buddy's jeep which threw the belt. If everything spins fine with no wiggle then the belt most likely just came apart as you were driving (Which I've had happen to me). As for the leak how hot did the truck get? I'm thinking it's coolant, p/s fluid wouldn't run all the way down to the bottom of the crank and that's quite a jump from the trans.

 

Sounds like a seized Water pump. That locks, the belt spins and burns, and then after effect is dripping coolant from the seized bearing. Happens all the time in BMWs, That is why I replace my waterpump whenever I notice even the smallest amounts of seepage when doing routine maintence.