To reach the 2nd round you have to earn 5 stars. For every race you can earn 3 stars maximum. Bucket list challenges also give 1 star when completed. So the minimum requirements are 2 races. But you can also earn 1 star in 5 races.
For all of the races I concentrated on meeting the requirements first and then chase the field to win the race. Usually the opponents drive in one big crowd and the requirements can be fulfilled in the first lap or first 50% of the point-to-point races. There were only a handful of races where it is more helpful to stay at the top of the field and slowly work on the additional requirements.
For some requirements it is a bit difficult when you use the rewind feature. For example for drifts or combo-points. As the counter stops when you use rewind. And there is some kind of cooldown until the combo starts again. So you may have to rewind further than you want to.