#5 & #10
My understanding is that the model allows Justin to make a seperate decision to either wait or walk at EACH stop along the way. He can continue to walk or change his mind in light of new information (presumably in the form of a catchable bus, missed bus or continued absence of either)at each decision point. If the bus never comes he's making slow progress, if he can catch a bus at a later stop he's no worse off. BUT, there's the risk of getting caught in between and missing the bus.

i believe that tracks. though i should point out that my personal expertise is in type "A" behavior rather than mathematics per se.