Wow, from what you are describing it sounds like you have a leaky home.
I would recommend you have a blower door and duct test completed by a building/ home energy rater. They are the best at finding the leaks and recommending ways to seal your home in an effort to increase comfort and save energy/ gas at the same time. Make sure they are certified with either BPI or RESNET and are listed.
You might also want to contact your power company and ask if they have any FREE programs to help seal your home and make it more efficient.
Hope this helps.