Camping at the Wall

Hi! May you help me to clearfy some points?
First of all it isnt very clear on the map where is xizhazi village. I see 2 places with that name,one is 5th Team ,the second one is 2d Team. Which of them do we arrive by H25 bus? It is important cuz we plan to begin from Beijing Knot and walk till Mutianyu.
Second question is about coming back to downtown. So we walk to Mutianyu and then reach ticket office or what? How can we find the exit from Mutianyu? Is it a long way from Knot to the Mutianyu exit? We plan 2 days trip(one night,2 days)And do we need to pay if we come there from Jiankou?