Checkout NewAir AI-100R Portable Ice Maker Reviews 2018 Below.
The best way to use this is to turn it on when you need to make ice, unless you are going to need a lot in a hurry - then you can freeze the cubes ahead of time.

1) How much ice does it make?
Well, each time it makes a batch, it makes between one and two cups ... that's every 6-10 minutes. So in an hour, it will make 6-10 cups of ice.

2) How much ice does it hold?
I was able to empty 2 trays into a gallon freezer bag (barely), so I'd say that it holds about 1/2 gallon of ice before it automatically shuts off.

3) Do you need to keep it turned on?
You can, but you don't have to. Put the ice you've made into your freezer and turn it off. When you aren't going to use it for awhile, you drain any extra water out so that you can be sure your water to make the ice is fresh and healthy.