Beans which are grown for dry seed should be allowed to dry on the plant, to the greatest extent possible. The only reason to pick the pods before they are fully dry & then dry them indoors would be to avoid spoilage, such as if a period of extended rainfall is expected.

While it is possible to harvest beans as shellies & get a second flush, it is unlikely that it would have time to fully mature in our zone. If you want to try it, I would recommend picking all of the pods from a few plants - rather than picking pods from all of the plants - and leaving the rest of the plants for dry seed. Provided that you strip all pods from the plants used for shellies, that should stimulate them into producing new flowers. Chances are that you will be able to at least get some snaps from those plants before frost.

That was a perfect, clear answer. Thanks for the help Zeedman.