Pseudo random numbers always have a seed. What happens on slide 21 is that you let the random library pick one; that is, however, not reproducable. If you look on slide 19, you see that you can pass a seed to the engine.
Yes, there are several directions possible. You need to use the random number generator to decide which to take. There are a few possibilties on how to do that, but if you draw a random number c between 0 and 1, you can pick the left move if c
Yes, there are several directions possible. You need to use the random number generator to decide which to take. There are a few possibilties on how to do that, but if you draw a random number c between 0 and 1, you can pick the left move if c