where to find the "authorized translators" to do Chinese translation of birth certificate

my fiancee and I wanna register marriage in Den Haag - the Netherlands, but I have some questions about my birth certificate.

I was born in China and I moved to Hongkong when I was 4 years old. My original birth certificate is only in chinese.
When I moved to Hongkong, the Hongkong immigration office gave me a chinese pinyin english name; Wong Chi Man.
Then I added my christian english name, Mary, behind my pinyin english name when I had my adult Hongkong ID card, like in my passport.
In my case, is there any way to translate my chinese birth certificate to english and have it stamped by the proper legal authority? Will it have my english christian name up front?
I've contacted the immigration office of Holland and the staff there said that I need to have 2 stamps on any legal paper so do you know where exactly I can have both of my stamps?

Also, I'm thinking about registering our marriage in Hongkong, as it seems to be easier; just need to bring the passport and hand in 300 HKD. Would this Hongkong marriage be legal in the Netherlands?