有冇資格移民美國...?

The marriage certificate from China will not be any problem.

All documents such as birth certificate and marriage certificate are required to be translate into English. The document needs to be certified by some "official", the level of "official" may be different for different application. I know for Green Card applying citizenship, the translation only needs to be certified by Public Notification which most bank can do it. In your case, the translation would likely need to be certified by Court which you can get it with a fee.

A lawyer or professional who are working for this could save you a lot of trouble as they may know very well about where to get all these documents. Also, they could have some checklist to ensure you won't miss anything to delay your process.

I don't think any forum could give you any legal advice. The max you can find are some pass-experience of people's application which the information could be outdated. (The US law changes all the time)

To get the best advice if you plan to DIY:

You should get some advice from the Official US consulate in Hong Kong. Only information from an Official website are trustful:
http://hongkong.usconsulate.gov/ You may want to give them a call and read all details in the website. Another good website to read is http://www.uscis.gov

For 良民證, I think you can ask the HK police department about where to apply it. If they are not the person in charge, they may point you to the right person. Also, if you were living in other place beside HK, you may need 良民證 from there too.

Have someone guide you through the application may save you a lot of trouble. Likely, the lawyer's assistant will do all the work, so the charge may not be as horrible as you thought.

no problem, but you need to translate it into English copy legally. the lawyer should know what to do.

Your question is irrelevant to the immigration eligibility to the U.S.

However, in answering your questions, as soon as you can provide a official English translation, the U.S. Government will recognize the marriage.