I didn't have a chance to visit Mopanshan, so can't comment as to the forests there.

The old growth forest is in Ailaoshan National Nature Reserve, which, as its name implies, runs along the Ailaoshan Range.

It's definitely not all old growth. A driver friend of mine used to haul lumber off the mountain in the 80s. On Google Earth you can see various rural roads snaking up into the mountains, so most of the logging probably would have taken place close to these. But most of the mountain range is pretty inaccessible, and it's here that the older trees, and animals, are most likely to be found.

As others have already answered, the Red River's source is in Dali's Weishan County 巍山, where it's little more than a trickle. The Red River had at least three different names within Yunnan that I know of:
Lishejiang 礼社江
Yuanjiang 元江
Honghe 红河

I'm all for allowing street vendors to do business, for allowing different levels of the economy to flourish. But these Xiaoximen vendors have gotten way out of hand. The traffic jams radiating out of Xiaoximen have just gotten ridiculous. It used to be on a bicycle I could weave my way around any traffic jam, but I recently spent ten minutes on Renmin Road approaching Xiaoximen from the west, in pure gridlock. Even the pedestrians were in gridlock. I'd never seen anything like it.

April Fools' jokes aside, there is in fact a piece of territory which reminds me of this story. The Jinsha (Yangtze) River usually forms the boundary between Sichuan and Yunnan. But one little piece of Yunnan's Yuanmou County (Jiangyi Township), juts up north of the river, seemingly annexed out of Sichuan.

The prettiest time of year to visit Puzhehei is June, when the lotus in the ponds bloom with pink and white flowers. Bear in mind, this is also the season when Puzhehei is flooded with Chinese tourists and room rates skyrocket. However, you can always stay in a hotel in Qiubei city, which don't go up during lotus flower season.

In just a few years, it will be possible to take the new Kunming-Guangzhou high speed train direct to Puzhehei, which will have its own station.

Seven years later, and while the 80 yuan maintenance fee is still posted at the main entrances to Dayan, no one's collecting and no one's paying.

Too bad the same can't be said of Heshun (和顺) near Tengchong