Is the location of this gas shut off valve for the furnace OK or should it not be behind the panel?
The gas cock should be on the exterior of the appliance. Imagine changing out the furnace with the gas cock in the furnace.
That makes sense! Another question that lies within the realm of this post I think…I’m sure a shut off valve would be required for this natural gas fed fireplace as well?
Yes, yes it would.
Yes. But it doesn’t have to be right at the fireplace. Log lighters like that usually have a key at the floor adjacent to the fireplace though
The gas cock for the furnace should be in line above (before) the sediment trap.
Just to add. I see no tape or pipe dope on the gas lines. safety hazard…