Do I need a Chinese visa?
If you want to travel to Mainland China, whether for business or tourism, you are required to have a Chinese visa obtained from a consulate in advance of your trip.
You are exempt from applying for a Chinese visa if you travel and stay only in Hong Kong or Macao for some days.
http://www.immd.gov.hk/ehtml/hkvisas_4.htm
http://www.dsi.gov.mo/announcement/E002_index.html

I got the China visa at the embassy. What does this visa mean?

CATEGORY: L (tourist visa or visiting relatives) - there are other types, such as F (for business or short-term study), X (student visa), Z (work visa)
ENTRIES: 01 - there are other types, such as 02, M (multiple) and 00.
DURATION OF EACH STAY: 090 - there are other types, such as 030, 060, 120, 180.
ENTER BEFORE: 23FEB2006 and ISSUE DATE: 23NOV2005: 3-month visa

If you enter into China mainland before Feb. 23, 2006, you can use this visa. The 90 days of duration of stay is calculated right when you enter into China mainland through customs. Suppose you enter on Jan. 3, 2006, the visa is valid until April 2, 2006.

And if you want to go to Hong Kong and return to China mainland on Feb. 12, 2006, you cannot use this visa though it is still ENTER BEFORE Feb. 23, 2006. The only 1 entry has been used up the first time you enter. If it were a 02-entry visa, you would use it again.

With an F visa, what can I do in China?
F visa is issued to applicants who are invited to China for business, research, lecture, scientific-technological and culture exchanges, short-term advanced studies or intern practice for a period of no more than six months.

I am going to mainland China, then to Hong Kong and back to mainland China. Does this mean I must have a double-entry visa?
Yes. Although Hong Kong SAR and Macau SAR are part of China, they have different visa systems from China mainland. Each time you enter into China mainland, one entry will be used up.

If I want to stay longer in China, can I have my visa done without leaving China mainland£¿
Yes.
If you are holding an L visa, technically you can have it extended twice, with 30 days of each time. If you want to stay longer even than that, you can have your China visa converted to an F visa through a Chinese visa agent.
http://www.cn-visa.com/l_f_conversion.asp

If you are holding an F visa, you can simply have it extended for another 3, 6 or 12 months. http://www.cn-visa.com/f_visa_extension.asp

The visas issued when you are already in China mainland have NO limitation of each stay. It means if you wish, you can stay as long as your visa duration without leaving. The entry (ies) is for your expected or unexpected travel. You don't have to leave.

F-visa holders can stay in China mainland without leaving for consecutive one year, which is calculated from last entry date.

I have a double/multi-entry Visa, but have 60 days limit for each stay. How can I remove it?
Double or multiple entry visas (either an L or F) issued by overseas Chinese Embassies, Consulates, visa offices usually have limitations of each stay. The limit can NOT be removed in China since December 2004. Instead you can apply for a new F issued by Public Security Bureau. Your previous L or F will be cancelled since you can NOT have two valid visas simultaneously. Beijing LEEO can help you do that.

I am not staying in Beijing. Can I still get my visa extended through your office?
Yes, definitely you can. We have many faithful clients throughout China. For the processing procedure, please refer to the following link.
http://www.cn-visa.com/visaoutbj.asp

How can I get the "Registration Form of Temporary Residence", which is required to do visa extension or conversion?
Foreigners are required to register in the local police station within 24 hours of arrival. When you get a new visa or move to a new place, you need to redo it.
If you are staying at a hotel or hostel, the staff there will automatically do it for you. If you ask, they will give you the form. Please make sure they stamp it with the hotel or hostel' seal.
If you are renting an apartment or staying with your friends, you need to go to the local police station yourself. Normally, you are required to take the following documents:
Apartment rental contract
Passport
For the first time registration, you'd better ask your landlord to come with you. Or at least take one copy of the landlord's ID.

There is some company that intends to employ me. Can I avoid the Hong Kong visa run to get a Z visa? Or can I outsource the application to you to make it more efficient and quicker?
Yes, you can. Please find the documents required to do the whole work visa application (including work license, invitation letter, Z visa, Alien Employment Permit and Residence Permit for work application).