Transportation options in China?

My friends and I are going to Beijing and Shenzhen for our trip. It’s going to be a DIY adventure backpacking, so, we’re not on any tour package of some sort. We’ve heard some tips from my companion’s brother who went on one of those international dating socials. Unlike him, we’re booking and planning on our own, so we’re not so sure with our itinerary.

Our main concern is how to go around in China like generally speaking. Are there cabs around? What is the schedule for buses to and from the airport coming from the central business district. Can anybody help? Thanks a lot, guys.