Welcome to Just Answer. I will do my best to fully answer your question(s).
The only way you can repair your leak is to shut the water off at the main in the street. (this will entale calling your local emergency number as it is a weekend.-the water utility may have a number listed but if not, call the police department) Once the water is shut off you can cut the piping in two places, once outside the foundation wall and once inside. then remove the piping in the wall and purchase a section of pipe long enough to replace the old one and coupling it back together.
Any idea what a reasonable plumber should charge (I live in Missouri) if I do the digging down to the pipe?
Also, how much space would he need to connect the new piece to the copper line outside the basement wall? Inside the wall should be easy, but outside the house is a real bit#@!
I would ask again about a pressure reducer on the outside of the house? Bad idea? Good idea? Is it even an option?
Installing a reducer is not an option. you need to shut water off in order to install any type of fitting or material. There is an option of freezing the pipe but thats gonna cost labor. It costs nothing for the water dept to shut the water off even on weekends. As for the repair you will definitely save alot of money doing you own digging! I would get at least a 3' by 3' area against the foundation wall. As for plumbing costs in the neighborhood of $200 an hour for the holiday. Probably take 2-3 hrs once the water is off. I assume this leak is BEFORE your water meter so if you can wait until monday plumber will be much less. The water running before the meter isnt costing you anything. If you can go with out water til monday have the water dept. shut it off now then repair on monday.
I can shut off the water with no problem. It should be able to wait until early next week, since the leak is outside. Unfortunately, my meter is over 100 feet away from the house, so the water is on my dime.
Since the line is copper, will he solder or how will he join the two ends?