When stored, charcoal absorbs moisture easily and then doesn't light or burn well. You can prevent moisture from getting into the charcoal by storing it in an air-tight container. If properly stored, it can last indefinitely.  Charcoal can be easily stored in food storage buckets or used laundry buckets. You can lengthen the storage life of charcoal and increase the convenience of using it by sealing smaller quantities in food-saver bags and then storing those bags in your bucket. I plan to store the amount of briquettes I need to achieve 350 degrees in a dutch oven. This amount varies depending upon the size of your grill or dutch oven. Read here for more information.
You probably also want to store newspapers or lighter-fluid in order to light the charcoal. A chimney makes starting the charcoal a lot easier. I would also recommend purchasing a dutch-oven, volcano stove, and/or charcoal grill. These are uniquely suited to cooking with charcoal.
You should never, never, NEVER use charcoal indoors (or even in an open garage)! Charcoal creates a lot of carbon monoxide and will kill you. Always use it outside.