When planning your career path, the best choice might be to "know yourself".

这个现在分词短语作状语，带有时间连词when, 其逻辑主语并不是句子的主语。这就够得上悬垂分词的标准了。但悬垂分词并非都是不可接受的，只要不至于导致误解或产生歧义，还是可以接受的。但在正式的写作中，这种结构还是应该避免的，即改为when引导的时间状语从句：When you plan your career path, the best...。

And there isn't going to be as much room to wear all these different hats and kind of pinch hit when needed.

when needed = when it is needed. it 指代to wear all these different hats and kind of pinch hit。