1. What do you define as "good"?

We explain that here: https://80000hours.org/career-guide/how-much-difference-can-...

2. What do you define as a "good career"?

We explain that here: https://80000hours.org/career-guide/job-satisfaction/

3. What do you consider as a "hugely positive impact on the world?

Helping a lot of people in a really significant way!