If you find lumps in a can of paint that you need, you can "push" them out. Cut out a circle from a piece of wire screen slightly smaller than the can's inside circumference. Put the screen circle on the surface of the paint. With a little help it will sink to the bottom of the can, taking the lumps with it. Another way to salvage lumpy paint is to strain it through an old nylon stocking.
Look for dirty spots in your insulation, which often indicate holes where air leaks into and out of your house. You can seal the holes by stapling sheets of plastic over the holes and caulking the edges of the plastic.