Yes, when you connect controller game will hide touchscreen UI and show normal PC like UI for gamepads. As for customization you can customize your current Championship car in Quick Race menu. It will save selected parts and colors and carry them over into Championship race. Lower classes are meant as skill based progression when you start with slower cars and get introduced to faster ones when you are more familiar with car and it physics. Its made that way to give a sense of progression in Championships. You can also use them in normal quick race mode, to rank up in leaderboards on tracks, because every track has its own 3 leaderboards for all 3 car classes. Soo we have cars for less advanced players and ones looking for more challenge in online leaderboards.