Kettlebells and the tabata protocol

Hey there everyone!
i found the pdf 101 kettlebell workouts by david whitley and it suggests using the tabata protocol in combination with kettlebells.
i want to start a tabata protocol with kettlebells and got a few questions:

1:should i take a heavy kettlebell or a light one?
2:how often do i need to do this(per week) to see some results?

thanks in advance
alex