Tianmen Mountain hiking

Hi There,

I am Nicole from Malaysia and a help from you to study on the Tianmen Mountain hiking, Zhangjiajie.
The information that I need is:-

1. When would be the best time to visit this place
2. How many days do you need
3. How much would be the cost / pax if on group of say 10 pax based on bag pack costing.
4. The mapping of the spots including Tianmen Mountain, Fenghuang, Tianzi Mountain, etc. as I cannot imagine them

Thank you very much.

Regards
Nicole