Note that, over the years, the onset of the (relatively) rainy season, in Kunming at least, varies from about mid-May to early June - no guarantees.

@ newlaowai: Well, I guess I got that wrong. Y2000-2500 per month is indeed enough for rent. My flat (old building, 7th (top) floor walkup: bedroom; 2 glassed-in sun porches, to south & north respectively, the one to the south provides considerable heat when the sun shines, which is usually; sitting room with furniture; kitchen; small office; old-style toilet with shower; solar heated water - costs me Y1000/month, plus peanuts for gas & electric; I signed lease in early December. A particularly good deal, I think, but you can certainly find a place for less than Y2000/mo., but of course it depends on what you want to pay for.

Plenty of migrant workers have gotten ripped off, legally or otherwise, by both Chinese-run and foreign-run enterprises near the coast, where they have no union protection, legally or illegally.
If a school offers you a bonus, you can be sure that your regular pay is lower as a result.

Why don't westerners here do it? Perhaps because they have some cultural reason not to?

Yuanyang is indeed worth the trip - very dramatic results of some centuries of work by the local Hani ethnic minority people - though you're only going to be here 4 days so I don't know what priorities may apply. Rice terracing, major or minor depending on slope and population pressure on the land and on the socio-economic status of the farmers vis-a-vis other farmers nearby, can be seen elsewhere as well (nobody goes off building rice terraces for the fun of it), but I can't think of anyplace right near Kunming (which is built-up and anyway pretty flat) where you will see anything dramatic.