chinese visas
Visas are important. If there's any section of this site where you should get more up-to-date information before taking any action, it's this one. And all the others.Chinese tourist visas (L)
Easy to get hold of, you should be able to download the application form from an embassy very easily (UK, US, list). These are available in 30, 60 and 90 day flavours, and the embassy will issue the one it thinks most appropriate for your stay. What this means is that if you put down a huge list of cities you want to visit you are more likely to get a longer visa than if you simply write down Beijing. Don't mention any plans to visit sensitive areas ( Tibet is the obvious one, but I would skip any border regions), and don't worry about this list - you'll never see it again, and you aren't obliged to stick to it.
Working on a tourist visa is illegal, and the PSB do take a dim view of it. As always, things are flexible, and it depends on the local branch and their relationship with your employer, but I wouldn't risk it. Beware of employers who ask you to come in on a tourist visa and say they will change it later - it's not always as easy as they make it sound. A trip to HK or Korea may be necessary, though hopefully avoidable.
Chinese business visas
To get one of these, you usually require an official invitation from an authorised body. Business visas can be valid for up to 1 year, but you will need to convince the embassy you need to stay that long. These are easily available in Hong Kong for 6 months, multiple entry. Working on these is illegal again, but perhaps less so than a tourist visa. If you don't annoy the PSB (and your employer doesn't either) then you'll normally be ok.
Chinese work visas (Z)
This is the one you really want, unless you are opting to freelance on a business visa. Once you've found an employer (who is licensed to employ foreigners) they issue you with an invitation letter. This, and your passport, go to the Chinese embassy for a while, and when they come back your passport has a new stamp in it. Note, this stamp only permits you to stay in China for ONE month. This one month is when your employer should apply for your residence permit (often called a green card, because it's green, though this is where it's resemblance to the US green card ends) which then takes precedence. Your residence permit will be valid for the length of your contract, up to a maximum of one year (longer periods are possible, but only for people the government wants to be best friends with). Theoretically, you should be able to travel with only your residence permit, but in reality everyone will ask to see your passport as well. A good rule for China is to take every document you have everywhere you go anytime you think you won't need it.
changing visas in China
This can be done, in certain circumstances. To go from a tourist visa to a business or work visa, you are going to need the assistance of your employer or an agency (check ex-pat mags for ads). Agencies can be expensive, and you may need to hand over your passport for a week or more while they send it to a tame policeman in Jiangxi. Going from a work or business visa to a tourist visa should be easier, if you explain that you've finished your work and wish to do some travelling. Ideally though, get a longer residence permit and travel on that.
registering at a police station
All foreigners should register their stay at the local police station
within 24 hours of arrival. If you are in accommodation which usually houses
foreigners (a hotel, or a foreign teacher's building) it will either be taken care of or unnecessary. If you are staying in
a Chinese apartment, it is something you should do. If you don't, it's possible you will get a knock on the door from some
(usually) friendly policemen who will reduce your fine greatly if you are friendly, apologetic and sign a little piece of paper
acknowledging your guilt and determination never to breach the laws of the People's Republic of China again.
foreign expert's certificate
These are a relic from the days when being a foreign expert meant you were a foreign expert, not a 21-year-old chancing it as a TEFL teacher and writing home to his mum about how he's an expert at something. They are only useful for changing RMB into foreign currency at Banks of China (which is a hassle I won't go into). They used to get you discounts, but I don't know of any they get you now. I always hand mine over with my passport and residence permit when checking into hotels, and ask for a discount just after they nod approvingly at my status. It doesn't get me any discount I wouldn't have got anyway, I just like showing off.
visa problems
I know a number of people who've had visa problems for one reason or another. It seems that while the official fines are very hefty, remorse and contrition go a long way and these fines can be reduced substantially. I know of one case involving three people who'd taken longer than a month to get their residence permits (they were on work visas). They were taken down to the police station and given a bit of a lecture. The one girl who nodded politely and apologised walked away with no problem. The other two were argumentative, blamed the school, and were fined 1500Y each.