Hi babyarnold and welcome to coffeesnobs.
It all depends on how much coffee you drink a week.
If you go through 250g per week (approx twelve to 15 cups) then 1 kg will last you a month. I am not sure what Andy says is the maximum time to keep CS Brown beans.
As for storage. Keep the beans in a cool dark cupboard. Browns come in a large 1 kg bag (for 1 kg. just take the weeks supply (eg 250g) and put them into a airtight cannister.
Make sure the larger bag is well sealed so air cannot get into them