Can a Dr's office secretly have audio on its security cameras in the waiting room and hallways so administration can listen in on employee conversations at front desk?

Answer 1

The answer will depend on the laws in your state. Generally you have reduced expectation of privacy at work, and if the recording system is visible, they are probably OK in recording.

If you are terribly concerned you should speak to a local attorney.

It is much more likely that they are violating the rights of patients than employees. Patients have every right to expect privacy and confidentiality in a doctor's office.