Most chickens can live without food for at least 7 days.
However after about 2 to 3 days without any feed the chickens may begin eating their own eggs that they lay.
Chickens are pretty good at self supporting themselves if they happen to be left alone without food for longer than a few days.
However if you're gonna be gone away from the chickens longer than a few days it would be best to have someone come over to take care of and feed and water your chickens so that they have plenty of food and water.
Chickens do stop eating the chicken feed when they are full.
Just like humans stop eating when they are full as well as other animals the chickens do know when they are full and will stop eating.
So just make sure you keep out enough food for the chicken to eat through the day and they will know when they are hungry and when they are full.
Chickens need plenty of food to fatten them up and to allow them to lay eggs.
Also be sure to keep water out for the chickens at all times so they can access water when they are thirsty.
The chicken will drink when they are thirsty and stop drinking when they are not.
I would not recommend leaving chicken feed out all night though because other animals could be attracted to it and chickens will sleep at night and not come out to eat anyway.