I will say start talking about general topics like weather, studies, and books. After that, you may gauge what topics you should avoid to talk based on the other people reactions.

I would say religion and politics are the big ones

I believe that until you are more familiar with people they generally don't want to talk about any topics which have strong emotions attached too them

Nothing is awkward if you don't think so.

From personal experience with Chinese people it's awkward if you ask details of their salary, trying to convince them that Taiwan is not a country, saying that you hate gay people.