Hi, the shuttle bus should be Line 2, which will drive you to Xidan in one hour. Currently, there is only one kind of train from Beijing South Railway Station to Tianjian. It is the express intercity train (start by 'C') which just takes 30 minutes and 56RMB/person. Of course, you could catch a regular train from Beijing Railway Station to Tianjian, which takes about 2 hours and 19RMB.

Is the restaurant should be Dai Jia Cun (傣家村), supplying food from Yunnan Province? This restaurant's average cost is about CNY40~70/person, acceptable~ You could find it at 80, Tiantan Dong Lu (very to the south or east gate of theh Temple of Heaven).