G'Day peoples,
I know I do not need a visa as both my stops in Beijing are less than 24 hours. I have to change terminals, after reading some of the replies here, it is still unclear.

In my transits, am I free to walk around the whole airport? Or are there certain areas for transiting people? If so, is there a map of this area, so I can see what services are available there?

Because, as I read it, I can catch a bus to transfer terminals, what is to stop me from taking a wander outside? Not that I want to get myself in trouble.
Thanks in advance for your help!