I can only speak from my experience in China. I know next to nothing about teaching in other countries bar what I've read here.
It's difficult to give even a ballpark figure regarding earnings because each city differs in their pay scales. Add to that the possibility of working for either a public or private institution. Private ones pay more but demand more of your time etc. From my experience, private institutions in China can pay anywhere from approx 8000RMB/mth up to about 17000. It depends where and upon your workload (hours worked). Most private institutions don't provide accommodation so you'd have to pay for that, as well as utilities and all other living costs. If the salary is only 8000, and you work in a city like Shanghai or Guangzhou, for example, you won't have much left out of 8000 unless you live in a terribly small apartment in an area that most wouldn't let their dog live in.
I prefer public colleges. The pay is lower (approx 4000 - 8000 depending on where) but the workload is light and accommodation is usually free, as are utilities which sometimes stretch to computer and internet. With such a light workload, you can do extra work during the week which tops your salary up and allows the lifestyle or spending habits you seem to want. if you're not much into partying, you can do a few tutorials on the weekends and earn even more.
As for sending money home each month, not worth it I'd think. I just convert X amount to USD each month and every 3 months I go to HK and deposit it there. How much you send home depends on how much you earn, and spend on living and partying here.
The students: well, in China, they're for the most part, nice kids. As in every classroom, you have the malingerers but they're not the rule. Most students here want to learn and once you've broken through the shyness barrier, they're quite a joy to teach. It all depends on age and motivation I think.
Teaching degree: in China, your degree will be enough to get a job. Some of the upper tier places want a TESOL qualification, but not all. Experience counts for a lot here. I have no TESOL, but have been teaching here for 4 years now, so it's easier to "land" a decent job. I'm not sure about the other countries but I'm sure others here will be able to fill you in there!
Good luck in finding the job you want and the lifestyle you desire.
It's probably the right place to say; when you go to another country to teach, it's not a good idea just to go for the partying and women, that kind of lifestyle still exists but isn't condusive to acheiving and maintaining a good reputation and here, in China, foreigners are all generally lumped together and if one does a bad thing, we've all done it, so beware!
Hope this helps!
