I don't know much about Taoism, but this is definitely an interesting topic.
1. 無為; as previous comments mentioned is "inaction". What I understood of its meaning via the series is, "inaction" does not refer to doing nothing, but rather to not involve the self with worldly affairs. However if there is a situation whereby you encounter injustice, Taoism would ask you to do the right thing i.e. there is a war, there's no need to volunteer to fight to end wars. If you see an injured person, the natural action will be to help this person and so you do it. It's basically a do what needs to be done if you chance upon an encounter.
They help the refugees because every human life is precious.
2. If we're talking about the same scene and same episode, IIRC what Chang Ge expressed was she dabbled on all sorts of teachings, and she disliked/disagreed with Taoism the most, because she feels it is the most ignorant path--but she was enlightened by "Inaction" in the end.
3. I haven't done much reading about Taoism, but I believe what it preaches is "go with the flow".
In the series, one of the scenes talked about how the river will always be flowing. A tiger can drink water from it, so can a monkey (some other animal I can't remember).. and them drinking from the river will not disrupt anything, the river continues to flow. It just had me thinking "in that case, I'd like to be the water in the river. I'd always flow, and part of me will be with somebody. I am probably being taken advantage of (by them drinking me), or I'm probably helping someone by letting them take something from me (drinking me). Whether it's the former or the latter, it shouldn't matter. Either way I will still be here, and I will still flow"
That's what I got from it anyway. Looking forward to read more perspectives about this ^^