You Ask We Answer.
Do security cameras have audio?
This depends on the camera model. Some will have built in audio included. An example of this would be a doorbell camera. They typically have two-way audio that will allow the end user the ability to talk down and receive audio feedback from the individual at the door. To determine whether your cameras have audio, research on the model number will need to be done or you can ask a local security professional about specific models that support this function.
Do security cameras need Wi-Fi?
Wireless security cameras do require Wi-Fi for networking. Cameras that are not designated as wireless will require a physical cable be ran to the camera for networking.