We will be arriving at Huangshan North Station in late November. Our plan is to go straight to Tangk

Yes. There are direct shuttle buses available at North Station to Tangkou. The bus fare is about CNY20 per person and the journey takes around one hour. The last bus departs at 18:30. If you take taxi, the fare is CNY200-CNY250 per cab. Actually, at least two days is needed to climb the mountain. If you want to do it in a day, you will need to take the cable car up and down and several sites may not be covered. I suggest you start trip at around 6am or 7am in the early morning. From Tangkou to Hongcun, you can take bus at Tangkou Bus Station to Yixian and then change to a minibus to Hongcun. The bus to Yixian is available at 07:20 and 13:40. From Hongcun to Xidi, the better way is to take a taxi with a cost of about CNY20-30. After that, go back to Yixian and then take bus back to Tunxi. As for the hot-spring, one is Zui Hot Spring in the city and the other is Snow Hot Spring in Tangkou.