But I have travelled most of the country a few times over, most recently about a year ago (actually, I returned to the US a year ago two days ago).
I don't know if you've ever been there or how much you know about the flying you'd be facing.
First, right now would definately be a bad time to go, but that could change very quickly. There has been a flurry of Maoist activity in the past few days and two days ago the King declared a state of emergency. Being a westerner, you're a definite target for the Maoists, especially if you get a paycheck. But then again, I've been real close to the Maoists before and had no problems, even though they blew up a police station while I was in town...
The flying: seems like it'd be fun! For me at least, but I kinda like to take chances (why I've been there a "few" times). Twin Otters and Do-228s do all the flying for the "tourist" airlines. That would be the Yeti Airlines, Royal Nepal, Gorkha, etc... They typically fly a full plane from Katmandhu into the mountain airports. The coolest of which is Lukla, it's at about 9,400 feet, maybe 2000 long, and sloped about 18 degrees. It also terminates at at 5,000 vetical face. But there is also a LOt of traffic to the Annapurna region, with flights into Jomsom, a few into Humde, and a bunch into Pokhara.
That's pretty serious mountain flying, with a LOT of other airplanes doing the same thing, Helicopters doing similar things, and other helicopters going all over the place. Also, they're pretty much always leaving Katmandhu in fog, then climbing along a radial through the clouds and hopefully seeing whatever pass you need to go through to get where you're going. It's pretty common to have those airplanes in and out of clouds while inside half-mile wide canyons with a few thousand feet above them. And they routinely squeeze under a rapidly dropping cloud deck to get through some of those passes, I've felt the downwash of a Twin Otter while I was at the top of a pass in the clouds.
So there's what I know about it. The cousin of the owner of Yeti Airlines lives in Seattle and owns a resteraunt downtown, if you're in that area.
I don't know much about the lowland flying in the country, other than there are a lot of F-27s, Hs-748s, YS-11s, 340s, and 1900s that are waiting to leave Katmandhu when the fog lifts. The names I remember on those planes were Royal Nepal, Air Buddha, and Necon Air.
Hope that's been of some help. I am under the impression that they hire a lot of American pilots, but I've never flown with anyone other than a Nepalese or Russian pilot. The "du" would be a fun place to live for a while, talk about inexpensive too!