New member in Hangzhou with some questions

[Zhejiang rider]

Hi I'm a new member looking to get into riding in Hangzhou. I've looked around using the search function, but unfortunately it raised more questions than it answered.

My first question is just on the legality of motorbikes in Hangzhou. The city banned bikes some time ago for the same reason all cities do (farmers ride bike, farmer look poor, bike make city look poor!) But from what I'm told by various people motorbikes were made legal last year so that rich Hangzhou residents could ride their expensive imported sports bikes. And these are the bikes I see most of. Apparently this info hasn't filtered down to all the cops yet, I'm a student and we had an meeting with a police officer at the start of the year, where he just told us motorbikes were flat out banned. But my university professor ensures me they're not. I also see people riding around on motorbikes who look far from rich. After reading this forum it seems motorcycle licence plates in Beijing and Shanghai are astronomically expensive. Maybe they are not in Hangzhou?

Second question is, I heard that getting a new bike registered with a new plate can be really 麻烦， so some people who are into motorbikes I know suggested I buy a used bike which already has registration and a plate. When I told this idea to some other friends they informed me you can't transfer licence plates to a new owner. But they were talking about cars. And after seeing many people on this forum selling licence plates it seems motorbikes have different rules.

I am looking at a bike at the moment, it's a Chinese Suzuki GN125 Clone which (I've been assured) is fully legal and comes with all the required paperwork and licence plate. The seller has even said he will help me with all the documentation to get the bike registered to me and legal on the road. When buying a used bike in China, what documents should I make sure the bike comes with?

When it comes to getting a licence, I already have a licence from my home country. Do I really need to go through the 麻烦 of retaking a test or can I just go to some tier 4 city and pay someone some cash for a licence? And a lot of the guides on exchanging your licence say to translate the paper part of your licence. But my licence is just a plastic card. And it's not specific to motorcycles, it's a car licence that says on the back I can also ride motorbikes.

Thank you for any answers to my long spiel