Chickens can be left alone for a few days but not a week.
If you need to leave your chickens alone for a week or longer you need to have someone come along and take care of them while you're gone.
Maybe find a good trusting person or post on Craigslist that you are hiring for someone to take care of the chickens.
The chickens need to have plenty of food and water.
A chicken coop should be cleaned out at least once weekly to clean out any chicken poop, debris etc.
Daily you should clean out any leftover feed and water to prevent rodents and other animals from becoming attracted to the chicken coop at night.
Once per year you should do a really deep cleaning of the chicken coop.
Chickens are smart enough to get in out of the rain.
I lived on a farm as a kid and whenever it rained the chickens would get in out of the rain and go into their chicken coop to stay dry.
So as long as they can get into shelter on their own they should do so on their own.
If the chickens do get wet some it's not gonna hurt them though.
Also it's best to close the chicken coop door at night to prevent animals and other things such as rodents etc from getting to the chickens.
The chickens will remain in the chicken coop all night anyway and won't leave the chicken coop until the next morning.
So closing the chicken coop door is recommended as it protects your chickens.
Also chickens can go all night without the need for water.
When chickens go into the coop to go to sleep for the night the chickens will not leave the nest until morning.
So the chicken will not need water through the night.
As long as you keep water out for the chickens during the day then they will be just fine.
There's no need to add additional water to the chickens water bowls at night as they go all night without drinking any water.
The same is true for feed.
You only need to feed the chickens during the day.
During the night the chickens do not need feed and if you put feed out at night for the chickens it can attract rats and other animals.