The 2 phase is the regular round and then the jump off.
Speed is a single class and who ever is fastest wins. I can’t remember if poles down count on the clock or instantly take you out of the running.
The Grand Prix qualifier is just that. To see if you’ll make it back under the lights later on. I believe clear rounds are what they are looking for here.
Personally I love watching jump offs, especially after there was a huge battle in the original round. It’s so cool to ‘make your bets’ so to speak to see who you want to root for.