Hi MHT,
Here are answers from coach Pedro Carvalho:
a) In general preparation phase 3 workouts per week, in specific phase reduce to two times.
b) Yes , general phase short time/distance to enhance speed skills , specific phase for muscular endurance , work on the anaerobic resistance
In Specific phase , one max strength training.
c) Yes , depending on the goal you are aiming for.
I hope this helps.
Jane