Yes. You can talk to people in Beijing, especially college students, about these issues and more. One of my friends is an ethnic minority in China and talked about these issues with Han Chinese folk with no negative consequences. Many young people in China are also ready to talk about LGBT issues. There is no problem.
As long as you don't try to subvert the government or anything, you can talk about it.
Yeah. That's precisely the idea behind "freedom of speech", that even if you're restricted in doing a lot of things, the restrictions on talking about is as little as possible.
Talking about it influences opinions, and when critical mass is reached, even autocratic governments sometimes are forced to abide by the consensus of their people.
Noone's claiming that China is a better or more progressive country btw, just that in this very specific regard, US is worse than China.
As long as you don't try to subvert the government or anything, you can talk about it.