Main water valve

Not necessary, but some people for safety they do

Depending on the time of year, this could be a very good idea. In fact, it’s probably a good practice to do anyways. If the waterline is not insulated going into the home and you’re going on vacation in the winter, the water could freeze and cause the waterline to burst inside the houseD cause flooding. So it’s a good idea to turn off all water and if you want to take the next step, you can turn off the water to the house and drain all waterlines that lead to the exterior of the house.

I certainly would close the main valve. The only reason you might want to leave the valve open for "safety" is if you have a water powered backup sump pump which uses your water pressure to pump water from your sump pump in the event of a power failure or if you are going away in the winter and you have a boiler that connects to the house water supply to maintain its required system water volume. I can't think of any other benefits to leaving the water on when you go away. You may also want to check the fine print in your insurance policy...there may be certain requirements if you will be leaving house vacant for a period of time.