Yes, you are right. A single-entry visa is enough, and if you want to live in China for longer time, you just can get your visa extended once for another 30 days(at most for a visa extension).

Thank you for the response. I was in China last year and I had my visa extended, but it was a horrendous procedure. It took days and I had to open a bank account with enough money to support myself for 30 days. I'm not sure if it was bad luck or what, but it wasn't straightforward or easy, so I'd like to avoid a visa extension at almost all costs.

After much searching of the Internet I found some suggestions that getting 60 days under a tourist visa wasn't that difficult if you asked for it, particularly if you had been in China before. Can anyone comment on that?

it is possible, but no one can ensure you with it. the duration of stay is generally 30 days. Whether you can get a 60-days visa or not is finally depend on the consulates. Of course, you get more chance if you have travelled to China before. So Good luck!