Extractor Push and Skills ree Help

Playing as the extractor and have a few questions regarding its Push and Skills trees. Still wrapping head around game mechanics but loving the game so far!

1. what does "affected crew dice" mean? One of the Push tree +1 to it. How does it impact gameplay.
2. Any push and skill tree suggestions? How should I allocate points?
3. Is there a system to reset skill and push points?

Thanks all!