Sons' citizenship from BC dad (right of abode from HK)

[BrianLam]

Dear Moderators,

I was born in HK in 1981 and got my British Citizenship from my father when he got the UK right of abode while I was teenage.
I suspect I am "BC by decent" but I have nowhere to confirm. (Just for clarity, I have BC passport, not BNO)

I studied in UK full time for 6 years, and have been working in HK ever since. Then I got married to my wife (Local HK ciizen) in 2009 and give birth to 2 kids in year 2010 and 2014.

Reading from other forums, I tend to believe that my sons could acquire BC by decent given that I have been staying in UK for over 3 years, despite myself is (likely) BC by decent.

1. Could you please help to confirm this understanding?
2. And, if I was wrong, is there anyway to grant my sons BC if our long term plan is to return to UK?
3. If I was correct, are High school/ University graduation certificates valid proof of fulfilling the 3-year stay?
4. As for my wife, I tend to believe I need to apply for BC by nationalisation. Am I correct to say so?

Allow me to say thank you in advance!

Kind Regards,
Brian

[BrianLam]

Dear moderators,

As I am currently applying for children passport from abroad, would appreciate very much if you could help to share your advise at yoir earliest convenience, many thanks!

regards,
Brian