我想問下如果o係香港註冊結婚後﹐可唔可以o係香港工作呢﹖

First of all, working and marriage are two different things.

Even though you don't marry to a HK permanent resident but if you get employed and you can then apply the working visa since it requires the employer to sign such form, then if you can succeed to obtain working permit, you can work in HK with such working visa and apply a temporary Hong Kong id card, thereafter if you stay HK for 7 years, you can get a permanent resident HK Id card.

If you marry to a HK guy, you still must stay in HK for 7 years to become a permanent resident.

FAQ from immigration department:

Q13: I am a Hong Kong permanent resident and my fiance is a foreigner with no right of abode in the HKSAR. Can she, as a spouse of a Hong Kong permanent resident, enjoy the right of abode in the HKSAR?

A13: Generally speaking, spouse of Hong Kong permanent resident cannot acquire the right of abode in the HKSAR by virtue of their marriage unless the spouse is eligible, on his/her own accord, for Hong Kong permanent resident status under any provision of Schedule 1 to the Immigration Ordinance.

你去灣仔入境處申請就得, 結婚前都可以, 香港是優待外國 PASSPORT.
朋友帶外國妻子回流香港工作, 工作証很快批, 不過, 隔一段時間要離開香港, for example : 去深圳 或 澳門轉一轉.

你是不可工作的。結婚後你可以用夫妻團聚理由申請移居香港，申請期間你只能以訪客身份在港停留一段時間，期滿可再申請續期；訪客身份是不能在港工作的，否則會影響居港權審批。
香港的政策是一視同仁的，不會因為你是否大陸人而有不同，只不過基於歷史理由，大陸人的審批權是中國公安部，而其他國藉是港入境處審批的。