Traffic is terrible. I was taking a taxi the other night and the driver literally had to come to a dead stop because of the motor bikes oncoming in our lane! If you are on foot, watch out. Thieves on motor bikes may snatch your bag. Law enforcement is absent. I got my car tires slashed, in front of the police station. Yes, cars are expensive and petrol is cheap. Plan on getting a car because the public transit sucks.
The weather is the same all the time, hot and humid. Some people like that, but just know that it will NEVER be at a comfortably cool level. NEVER. I sweat so much I get rashes. People here are lovely towards foreigners, not so much to each other. Chinese and Malay are constantly fighting for power and the Indians are on the bottom of everyone's list. Thankfully you are foreign, if you weren't and you said something against Islam or the sultan you might go to jail. Makes it a bit hard to have a democracy when you can't speak out against the ruling ..
Food is great, lots of variety and a wide range of prices. Booze are expensive. Easy to get to other places in Asia. Easy to get domestic help. The beaches in Penang? meh...if you want to swim with turds and jellyfish they are fine. Otherwise go to Langkawi.

I find a lot of these posts to be disheartening because of their low expectations. As a couple living and teaching abroad as long as you don't end up in countries where the standard of living is incredibly high the salary vs. living costs ratio should allow you to save at least 20,000 a year without even thinking about it. Double that if you actually concentrate on savings and even more if you work at one of the better schools. Lets assume you put away 20,000 a year between the two of you. It would take you 30 years at 7% interest to reach over 2 million. As someone rightly pointed out, who knows what cost of living will be then, but if you conservatively take 4% of that each year you will be getting 80k. Sure, inflation happens so that wont be worth the same, but you will be much better off than most and able to live a reasonably comfortable life.
If that doesn't sound good to you then there are easy things to do like putting away just a bit more now and/or reducing your overall spending. Life doesn't have to be about caviar dreams. You can get by pretty well on not too much.
Yes, 7% is possible. Lots of Vanguard funds will give you that.

Shadowjack, it means they will publish this information online and/or to all potential staff members. You know what you are walking into prior to ever having a real offer.

Given the options, I say do it via skype since that will most likely be what you are used to in terms of a, "So this thing happens in your classroom, what do you do?" sort of thing whereas if you record yourself and present that you will be giving them and you something to - to no end. Of course, if you have something you are comfortable with already, just go with that.
Yes, I have had a similar request. I have actually flown to the country/school (just a couple hours) and taught a lesson to real students in the school in order to get a job.

Based on your post I will assume two things which very much may not be true for people who teach in China, or may be so depending on the job they take. First, it seems that you have taken a job in an international wing of a national school. Secondly it seems that you were not in one of the 5 major cities where most people end up. I will proceed with those assumptions.

Ok, agree with your good stuff. Totally true and basically the big reasons people go to China are to save and because China is the new west as far as opportunities goes. Bad stuff, I have some qualms with. Assuming you are in an international wing of a Chinese HS,
1 Yes, they may not follow the western calendar. Why should schools in China follow the western calendar? Some do, some don’t, some mesh. Really depends on the depth of the internationalization of the school you teach in and the government’s stance to it. There are advantages and disadvantages to both calendars which you nicely point out later. 6 weekends in a row is insane, which also leads me to believe you were in an Int wing of Chinese school and not a full fledged International School.
2. This is true and can be frustrating. Yes, prices go up. Have you ever travelled on Christmas/Easter, etc. in the western world? Welcome to the eastern equivalent. Completely agree with the fact there a billion people moving around during these times, perhaps more like 1.3 billion give or take. It can be terribly stressful to travel inside China during these times, avoid it. Stay home or go abroad. At other times travel in China can be very cheap considering the breadth of the country and the service received.
3. Agreeing here with point 3. People are generally very nice once they know you, by western standards. They do spit, cough, pee, and stare. Remember that China is experiencing the most rapid movement of populace from the country to the cities in the world and most likely these people are first time city dwellers. Take it in stride, take it as the way it is. To do otherwise will drive you insane because that baby with the split pants who just pooped on the subway platform, that’s not the last time you will see something like that. Just remember, no one else blinked an eye.

4. Now that is just not true. Many people don’t speak English, but a lot of people do in urban centers. Yes, it is hard to get around even in the most urban places, but you can. Learning 100 words of Chinese gets you 90% of everywhere and having a friend who is Chinese gets you the extra 9%. Its odd that the poster says in section 4 that its hard to get, “clothing, and basic things” when in number 1 they say you can get everything on Taobao. If you live in an urban center you can get anything at all. The end. Yeah, you can’t buy your red cheddar at the corner shop but hey, you are living in a foreign country with different priorities. Take a cab ride or underground to get what you like in any major city. Its there, you just have to take an extra step for it. True, you need locals to open accounts and transfer money, which sucks.

5. The pollution is worse than you think. Really, it is. This is because you come from the west and because it is terrible much of the time even if you are from China. In this case it doesn’t matter much where you live. Pollution in China seeps into everything. Air is bad, water is bad, etc. you really have to look for the bright spots. I look at the AQI a lot for the major centers and much of the time it does read above the highly polluted levels, but there are cleaner days as well. My advice here is to just be careful. Get a mask, put filters in your home, watch the AQI and buckle in for the ride. If it’s not clean outside then watch a movie at home. Get out when you can.

As a general information I lived in a major center of China for a few years and am about to go back again. Yes, go back. Despite the warts there is something about China that attracts, besides the high salaries. It’s a place where things seem to be moving and shaking and if you keep your priorities straight you can probably find a nice little slice there. If you are a nature lover who is adverse to eastern culture you will hate it. Just choose carefully.