Obsidiaus there are 7 guides and 5 of them are from 3 months ago and only 2 are from a year ago.

Ok

I would like to speedrun a few challenge mode levels but there are no level speedruns, just the full challenge mode.

You do include the transitions in the total time it took you to best the cup but you only include the race times for your inn game time.

The character you choose does not really matter because they don't effect the stats of the car and I played as a few characters in the Egg 1 and I did not really notice a difference while driving or snaking. So it mainly matter if you choose a kart that can snake really good.