Reviewing Offer to Teach in Beijing

Hello All....You're help will be much appreciated! After a couple of interviews via Skype, I was unofficially offered a position to teach science classes at a new day school in Beijing. They have beenaround for 10 yrs but now will open the day school for grades 1-9.

I'm researching now before we go into anything official - i.e.negotiations. Based on the interview, the school's leadership team wants me in Beijing this summer for curriculum development. Long story short - the position they have in mind in more involved then the sample job description advertised. I've reseached as much as possible about living & working in Beijing online but I still have some questions.

-What's considered a decent salary and benefits package? The sample job description shared the benefits at 16500 RMB (net) with a housing allowance of 3000 RMB. They'll also give a flight allowance of 8000 RMB (reimbursed). I feel like that's low (and that all of the figures shared should be doubled) but websites say it's pretty good for an international school. I'm not trusting that just yet....They want me to be more active in the school's development, which wasn't advertised on the sample job description. I still have student loans, would like to live in a decent 1BR (CityWise Beijing - decent is starting around 10000 RMB), and want to save at the end of the month. Also, I have a terminal degree in the science field and 8+ years of teaching experience.

-Renewing job contract: I'm a little nervous moving so far for a year contract. I learned from my previous expat life that it takes a year just to get somewhat comfortable with a new country (on a basic level). What are some reasons teachers aren't rehired? On the flipslide, what helps a teacher stay competitive for keeping their position?

-I'm pretty tall -  about 6'. How would I get clothes and shoes? I'm not sure how convenient online shopping is for shipping to China - esp for tall folks like me.

-Is the air pollution really that bad? My top value is wellness and I see many yoga and meditation places in Beijing. But is it a place where someone can realistically stay healthy?

-Housing - What's the best way for newbies to look for and secure decent hosuing? I'll get temp accommodations for 1-2 months from the employer.

WiFi/Internet reliability - In addition to teaching, I'm considering keeping my online job. How reliable are the WiFi connections?

Much thanks in advance for any helpful info!