Does anyone perhaps know what bus to take from the South Bus Station to Chengjiang (close to Fuxian Lake)? Thanks!

www.gokunming.com/[...]

"From Kunming the most commonly used option is public transportation, as Fuxian does not have an airport or train depot. Buses headed to Chengjiang Bus Station (澄江客运站) depart from Kunming's South Bus Station (昆明南部客运站). They leave throughout the day as they fill with passengers, running from 8:30am-11pm. Tickets cost 20 yuan per person and the trip can take as little as an hour, but traffic conditions can push that longer."

Fuxian lake is pretty big, and the area nearest Chengjiang is still another bus ride away. You should take another bus once you get to Chengjiang. It would help if you have a specific destination in mind. And then take the bus, or local taxi.
Haikou is just over a third the way down the east side of the lake. It is an underdeveloped tourist village, it is quiet, and has both restaurants and guest houses, as well as being (in my mind) on the more picturesque side of the lake. Being on the east side it is not in the shadow of the mountains towards sunset, and stays lighter and warmer later.

Luchong Scenic area on the west side is somewhere I avoid, as too touristy.

Thanks for the advice!