Is there a bus to Songpan from Xiannanmen Bus Station? How long does it take?

I am afraid not. The buses to Songpan only depart from Chadianzi Bus Station at 7:00, 8:30, and 11:30. The fare is CNY 109, and the trip takes about 7 hours.

Yes, you can take a bus Jiuzhaigou from Songzhou Bus Station on the next day. The buses depart at 9:00 and 13:00, and the fare is CNY 33 to 40.

You are advised to book the ticket three days in advance. :)