Adding storage and organization is straightforward (file cabinets, rubbermaid tubs, etc.). IMO, you have a clutter issue which points to habits (our family had the same issue). When someone walks into the house, they should immediately put away or take care of what they bring in. For example, coat gets hung up, the bills are put in a bill tray, junk mail is immediate recycled, and purchased items are put away (with boxes and bags tossed out). This should take < 5 minutes. The other thing to do is spend 15 minutes each night cleaning and straightening. My wife and I do this after the kids go to bed and before we sit down to read or watch TV. Doing just these two things -really- helps keep the clutter at a minimum.
I keep it for tax purposes which means at least 3 years. All that info (and W-2s, etc.) go into a sealed folder and then the file cabinet.