Standing during the Service (no pews/chairs)

[TylerRay]

Why was/is that, Tyler, and what is the biblical basis for sitting while singing?

The Scriptures present standing as a normative posture for prayer. Kneeling is also used for prayer in Scripture. Sitting, to my knowledge, is never presented as an appropriate posture.

This article from the FPCS provides an excellent case for standing during prayer.

I don't know that the Scriptures ever present a normative posture for singing. I don't think that anyone would argue that sitting is the posture for singing in the same way that standing (or kneeling) is the posture for prayer.