Advice for Chengdu to Songpan by bus and Songpan to Huanglong by bus

Hi,
I am going to visit Huanglong and Jiuzhaigou from chengdu in late October 2016. I plan to take the bus from Chengdu to Songpan and stay one night to take the bus to Huanglong in the morning. Then I travel Huanglong done. I will go to JZG and stay 2 night.

1. Is there a bus from Chengdu to Songpan? Where should I get the bus at Chengdu? (Xinnanmen Or Chadianzi), When is the first bus going to Songpan?
2. Is there a bus from Songpan to Huanglong? In the morning, When is the bus going to Huanglong?
3. After I travel Huanglong, Is there a bus from Huanglong to JZG? When is the bus going?

Thank you,