I spent a month in China earlier this year. (It was for pleasure, not business.) It was an interesting (read: frustrating) experience from the perspective of access to the internet.
I didn't actually use Tor while I was there, so my answer doesn't include any details about bridges, pluggable transports, or other proposed methods for getting around the Firewall. I'll let other members of the group flesh things out.
In response to your questions:
- Probably. But if they were publicly advertised then the Chinese authorities would also know about them. Even if you thought you had found a safe mirror, and could access it either directly or via a VPN, you would have to be very careful about guaranteeing its authenticity and ownership.
- Another option would be to have a friendly party get it to you somehow. (Via email over a VPN... ?) Again, the catch is that you'd need to ensure authenticity of the binaries - by checking a signature/hash/etc. - in case your mail/VPN/friend is compromised.
- During my short time there, I think I managed to get through 3 different VPNs, with each becoming inoperative after a certain amount of time. I didn't use any of the paid services I know exist. (I refuse to pay for a compromised VPN service presumably owned by the authorities!) My technique for finding a new, working VPN each time was to ask someone. I was lucky enough to be staying in areas where there were either other travellers, or students. Asking someone over a beer seemed to be a lot less hassle than scouring forums full of out-of-date information. However, with all of this, I had no idea who controlled or owned the VPNs, so my browsing habits were strictly limited to things like checking email, Facebook, news at home, etc. (i.e. Reintroducing the convenience at the potential cost of being watched.)
- With regards to how China is blocking things, have a read of this post on the Tor Blog: https://blog.torproject.org/blog/closer-look-great-firewall-china
Again, I'll let other users comment (speculate?) on how best to circumvent the blocks.