My garden is about 15mtrs long and 6mtrs wide, my choocs have a 3 1/2mtr square pen at the top.
According to
www.poultry.allotment.org.uk 4 chickens need a min of 20 square feet. When Im away from Home I ask someone else to look after them.
Yes put to bed at night let out and fed/ watere in the morning.
My brother has a very secure pen, im not saying its totally fox proof but he dosnt put his birds to bed and in the last two years he has had them, so far no foxy loxy, He fills his feeders up once a week and that does the job, collects eggs every day to stop the hens eating them.
Hope this helps.