My info is taken from
@andrewilley 's incredible website about everything Port Orleans:
http://www.portorleans.org/buses.php
Yes it's true. The bus stops go in this order: (sometimes French Quarter) -> West -> North -> East -> South -> Theme Park
During the busy periods in the morning, the buses to MK will change routing: one bus will serve South only and leave for The Kingdom. Another bus will come and serve just West, North, East, and leave, bypassing South altogether.
The advantage of getting on an earlier stop means a better chance of getting a seat, or getting on the bus at all. The disadvantage is being on the bus longer before getting to the eventual destination. The later stops, obviously, everything is flipped: less time on the bus, itself, but it might be full.