I will go to Shangrila at 7 & 7 December.

Yes, it had very light snow in early Dec. Usually, the snowfall happens since mid. Dec.

Local bus station is 香格里拉汽车在客运站. And do you mean the Dukezong Ancient Town? If so, local city bus no. 1 leads there. If you cannot find it, just take a taxi to reach.

Yes DukeZong Old Town. Front the bus station, I should take bus no 1 to go to the old town, right? Do you know where can I find Hotel Shangrila E-outfitting?

Yes, you are right. The hotel is located at no. 9, Lunhuolang Road, beside the Giant Buddha Temple in the Dukezong Old Town. You can easily find it.

I have changed my hostel. I planned to stay at Shangrila Baita International Youth Hostel on the first day and will just strolling down the old town. The next day, I'll be staying at Shangrila Lo Lao Shay IYH and plan to visiti Napahai Lake and Songzanlin Monestary.

Anyone know if I can access to public transport easily from this 2 hostel?

And, If I want to go back to Lijiang, should I buy the ticket in advance, or I can buy it on the spot?

On the first day, from your hotel, you can take a taxi to reach the ancient town. Or you can take bus no. 1. Or just hike there. The distance is just about 1.5 miles (2 kilometers).
But sorry, I cannot find the hotel on your second day. But to Napahai, you can take direct coach at Ancient Town Bus Station. To the Monestary, you can take public bus no.3 to get there directly. Actually Dekezong is not that big and you can cover all its areas iin the town by walking.
About the bus tickets to Lijiang, you can just buy them when you arriving at the bus station. Generally speaking, there will have enough tickets. Don't worry.

I see. Thanks for your reply. It helps me a lot. :)