Minimum FPS For Bank Teller

#1, good question.

For frame rate, the deciding factor should be whether one is trying to count currency or track objects passed between the teller and the customer.

In my experience, teller cameras are mostly used to just record an overview of the scene and the customer's face. In that scenario, you do not need a very high frame rate, 10fps would be more than enough to make sure you get enough changes as people moved their head.

As for VBR vs CBR, use VBR. Modern cameras almost never have issues using VBR and it will save significantly on storage.

You did not ask about smart codecs but I would suggest using them as well. Banks tend to want multiple months of storage and smart codecs are a good way to provide them that without reducing visible quality.

Related resources: Frame Rate Guide for Video Surveillance, 30fps vs 60fps Shootout, CBR vs VBR vs MBR - Surveillance Streaming and Smart CODEC Guide.

For Banks and Credit Unions etc we normally design around 25fps but never less than 13fps. Being able to recognize what has exchanged hands or even to recognize notes and do a recount is often a request. We have several Central Banks in our customer base.