Providing these water quality things are fine there is the chance that the cord running to the disposal has developed a short or a wire has become disconnected. You will need to disassemble the unit to verify all wires remain securely fastened. The last conclusion is that the motor has burned out, in which case you will need to replace the disposal unit.
Water leak detectors are alarms that alert you of leaks. They do not stop the water leak from happening. They also do not stop the leak after it happens or turn off the water line repair valve. You will still need to turn off the water valve yourself and contact a Utah plumber to come check out the plumbing issue.
If you bought the same unit it should line right up, if you were unable, you will need to remove or add length to the existing piping. This may require you to splice together copper with plastic, don't let this scare you the hardware store will have all of the necessary parts.
A plumber becomes a journeyman once they complete their apprenticeship program and they can apply to be licensed. Most of the plumbers today are in the field of journeyman. To get a license to be a journeyman, you need to pass an exam and pay a licensing fee.
As with anything, when you are not sure how to fix a plumbing issue and when you don't have the proper equipment, you should contact a professional. They can usually find out what the problem is and resolve it for you in a short period of time. They will also be able to tell you if you have any other problems and water line repair they can suggest resolutions.
Turn the water off at the main shutoff valve at the street. You should be able to take a pair of pliers(or your bare hands) and turn the valve at the water meter to shut off the water to your home. Once you have shut off the water you can cut the pipe around the leak and make the repair.
Be sure to choose a licensed glass shop in your area. There are a lot fly by night shops out there. You pay a lot of money for your vehicles so you want quality work at a fair price. Do the homework before you have this procedure done because proper preparation before installing a windshield will keep your car from having rust issues which may cause water leaks.