Good question! I‘m not that deep into the technical aspects but Chinese companies that work with foreign companies would have to work with the government and other Chinese companies that control internet access in China to circumvent the firewall legally. The process is likely limited and heavily monitored by authorities. Same would go for Chinese companies with storefronts in the global web. They would need to access our internet regularly but I assume their access is limited to some degree.

I imagine unless you‘re a big player it can be quite the hassle so many Chinese companies would rather work with domestic companies than with foreign ones. I think this is one major reason why many contracts with Chinese companies can only be done through middlemen. As an outsider, you can‘t get full access to their industry because you have no means of contacting all these little manufacturers yourself.

But again, I don‘t actually know for sure what these processes look like. Maybe someone with actual experience can shine a brighter light on this.

All company VPNs I've used limit the tunnel to the intranet, the internet doesn't go through there. But that's a matter of choice I guess.

Most likely split tunnelling

But idk anything