The connection to the meter appears to be a compression fitting, but it could be a union. Have the meter shut off, then relieve the pressure in the line either by opening a faucet or with the stop and waste on the old valve. Disconnect the compression nut or union. Remove the old valve at the elbow. If there isn't enough slack to unscrew it, you can unsolder the elbow. I'd avoid that is possible, but if necessary just be sure all of the water is drained from the pipe or the solder won't get hot enough to melt. Once you have the area cleared out, you would reassemble everything with a new 1/4 turn ball valve. I would not worry about a stop and waste, that's just to relieve pressure and that can be easily done at a faucet. The length of the nipple between the valve and meter will likely have to be adjusted, depending on the difference in valve lengths. If the connection is a compression fitting, the adjustment would be quite simple. Ball valves can be connected in several ways. One way is to sweat them, others screw on. I don't know about the small copper wires that appear to be connected to the compression nut. Perhaps one of the pros on the forum will clarify them.