Identifying My Main Water Shutoff Valve / Setup
Yes, that looks like your main shutoff valve.  It's normally the first valve on your water supply from where it enters your house, and typically before the water meter.    In my house there is another valve on the other side of the meter that makes it possible to swap out the meter without draining the house.

The copper wire is part of our house's grounding.  It jumps around the meter and ensures that there is an electrically secure path "through" the meter.  Because of the union joints and that some meter bodies are not electrically conductive, it provides a secure path.  Also when the meter is being replaced.