I know there are many threads here about e-bike stuff and I guess there would be an answer for my question in some of them, but just want to save time also to other users going through the 5-3y old info about the topic.

1) Registration office in city or south side ( 西山区 ) ?

2) What are the latest conditions, restrictions for registration? (could be link to local website )
As somebody wrote, He coudnt reg.his bike (72V ) ..
3) there are some papers along with the bike (fa piao, and some small card..reg.card? ) how to spot the fake one?

Any other additional info would be appreciated.

I believe the fapiao needs to be in your name. you'll need to take along your ID card or passport. If you have a resident certificate you could take that along too. I have no idea how strict they are right now.

I dont think you need have to register your ebike nowsaday.