Chengdu Weather(https://www.travelchinaguide.com/climate/chengdu.htm) is cold and dry during that time with a temperature of about 4~12C now and perhaps cooler later. While weather in Jiuzhaigou is colder than Chengdu at night, temperature may be below zero in the next few days and similar as Chengdu at daytime. You need to take warm clothing like overcoat or down jacket. Well, for the accurate temperature, you'd better pay attention to the weather forecast of Chengdu and Jiuzhaigou the dat before you go there.
It is about 5-6km drom Wenshufang Street to Jinli Street, you can take a taxi between them and the taxi fare would be around CNY10.

Thank you very much for your reply, sincerely appreciated :)