I've had no trouble at all with Chinese-made paracetemol aspirin etc. Local tea is excellent IF you like the way Chinese like tea - very unBritish, of course - frankly I don't care much about tea one way or another - local coffee beans are very acceptable, cost about $US 11-13 a pound, available only at a few shops or restaurants, mostly westerner-run.
I won't argue about 1980s-90s buildings (those before 1990 or so are being torn down) - Haali has a point about hygiene, but 'filthy' is too strong a word - but I will point out that many of them are homey, with trees and plants that haven't just been planted yesterday, residents that often know each other, kids running around acting like kids, old folks sitting outside chatting, a few dogs, not too many damn cars within the complex, etc. The newer high-rises here are more modern, but I find them sterile - however, I've never lived in one - wouldn't want to. There are also places in-between the 2 categories mentioned.
I've been here over 12 years.

I think Napoleon's advice is good, although I'd differ slightly concerning taxis (maybe it's where I live or maybe it's me, but I virtually never have problems with cabbies trying to over charge me - I often use them late after the buses stop, otherwise rarely) and buses (I find them no hassle). As for the underground, there are many places it does not go, including my area. Hard to imagine why you'd need a car - electric scooter, maybe.
5000-6000 a month is not unreasonable, but neither is 4000, depending on yr idea of lifestyle - Y4000/mo. is not poverty.
As for eating out, you certainly don't have to spend Y100 for a good meal - 3 friends & I ate our fill of a very good meal (4 dishes & a soup) on Saturday night for Y109 total, plus Y18 for 4 tall cold beers (local beers, not particularly good) brought in from the shop next door (note: menu was in Chinese only, as is usually the case). Plenty of more expensive upscale restaurants too. Any 'western' restaurant here is more expensive than where we ate on Saturday (which was really very good, although a bit noisy), but 'western' places, especially if foreign owned (several are pretty good), now tend to have good imported beer (considerably more expensive). Napoleon is right about Chinese restaurants tendering to groups, but you can eat a simple nothing-special meal on your own in many little places for Y20 or even less. Student canteens, if you're going to be at a university, are very cheap, and passable.
I disagree about the cost of haircuts and chocolate and milk (unless the latter has gone way cheap in GB lately).

The best way to learn Chinese would probably be to get a room in a family's house, if you can find such an arrangement, but that can require a lot of adjustment and is not something everybody would want to do.
Sharing with a Chinese person will certainly help you learn Chinese, but I wouldn't want to just show up and share with anybody until I got to know him/her a bit. I'd just get a room or something at first, until you figure things out on the ground.
I take it you've never been to China? Don't go around worrying about getting murdered.

Ctrip says several trains to Beijing take about 44 hours, but Z162, leaving a little after 9PM, is supposed to take only 33 hours.

Anybody know if this is true?

No Lao visa - the boat doesn't touch Lao territory.