Shenzhen hukou immigrates to Hong Kong.

I have been there before, so I may answer your question:

1. If you register now, it will take about five and a half years to queue up, and it will take about three to six months to apply for a one-way permit (proof of coming to settle in Hong Kong).

After you get the one-way permit, you can go to Hong Kong immediately and apply for a Hong Kong identity card. Please note that this is not a permanent identity card, but you can have the right of abode in Hong Kong or find a job in Hong Kong. After living for 7 years, you can apply for a permanent identity card.

When you get the one-way permit, you need to cancel your account in the mainland. You have no account on the mainland.

4. Both Hong Kong and the Mainland recognize the place of marriage registration. I got the certificate in the mainland, and a friend of mine got it in Hong Kong. The difference may be that the two places have different requirements for the documents required for marriage.