Q1 : I want to force the game to end midway.

You can retire (forced termination) by driving the wrong way in-game for more than three seconds when you've set your retire settings to "Yes" in the Car Data Confirmation Screen. Retire settings are valid outside of the In-store Interruption Versus Battle.

Q2 : What happens if I continue on the drive cabinet?

If you select "YES" on continue, the game returns to the beginning of the Game Mode that you were just playing. When continuing in the In-store Interruption Versus Battle, the players who selected "YES" on continue, will race again with the player who was in first place.