First Time at VEX - Having some questions Regarding Drivetrain

VEX V5 Robotics Competition VEX U
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  1. Some drivers like the way the drivetrain moves side to side (drift)
  2. Smaller wheels have more options for gearing the speed
  3. Direct drive is not optimal as the speed is usually not good and the wheels on each side don’t move in synch.
    By the way, if you have pneumatics or 5.5 watt (half power) motors, a six motor drivetrain is better. And also your drivetrain is currently very slow compared to other teams’ robots.
    Catalogue of Drive Gearings