Currently, does not apply to Hong Kong even though China is a contracting party to the Madrid Protocol. 

Prerequisite for registering Madrid trademark in China, The applicant needs to be Chinese (includes China and Taiwan, excludes Hong Kong and Macau) citizen, business organization, or other organization.

However, The Government was proposing for the Protocol to be applicable to Hong Kong. It is estimated that the earliest that the Madrid Protocol will be applied to Hong Kong will be 2019. 

You can pay attention to the dynamic of the official web：

https://www.ipd.gov.hk/eng/trademarks.htm

http://www.wipo.int/export/sites/www/treaties/en/documents/pdf/madrid_marks.pdf

Once registered, a Trademark is valid for 10 years, calculated from the registration date.

For continuous usage, after first 10 years, the applicant should keep on renewing it every 10 years.

Application for renewal of registered trademark shall be filed with the Chinese Trademark Office (CTMO) within 12 months before the expiration of the period of validity.

If no application is filed within said period, a grace period of 6 months is allowed with a payment of a surcharge. If there is still no renewal application filed within the grace period, the registration will be canceled.

After you file your trademark, you can't alter the trademark itself. The only way is to resubmit the application.

There are a lot of things that you can change in your trademark application, like applicant's name or address, but the trademark itself is not one of them.

Generally, the same text has registered first, the chance will be low to register the trademark including this text.

We are a trademark agency that we provide trademark protection services, including registration applications.If you want to analyze the availability of the trademark, you can send an email to us: mail@tmsearch.cn